| 1 | Worley Europe LTD | Unitedkingdom | Brentford | 27 Great West Road | London | TW8 9BW | worley.***** | 2001 | $607,416,686 | 1,200 | N/A | N/A | N/A |
| 2 | Foster + Partners LIMITED | Unitedkingdom | Battersea | Riverside | London | SW11 4AN | fosterandpartners.***** | 1967 | $466,568,704 | 1,618 | N/A | N/A | N/A |
| 3 | Canary Wharf Group PLC | Unitedkingdom | London | One Canada Square | London | E14 5AB | canarywharf.***** | 2013 | $442,169,291 | 257 | N/A | N/A | N/A |
| 4 | Building Design Partnership LIMITED | Unitedkingdom | Manchester | 11 Ducie Street | Manchester, Greater Manchester | M1 2JB | bdp.***** | 1961 | $189,019,473 | 1,328 | N/A | N/A | N/A |
| 5 | Populous LIMITED | Unitedkingdom | Upper Tooting | Carlson Court | London | SW15 2NQ | N/A | 1925 | $168,637,493 | 288 | N/A | N/A | N/A |
| 6 | M D T Design | Unitedkingdom | Micheldever | Unit 1a | Hampshire | SO50 7HF | mdtdesign.***** | 1997 | $160,466,893 | 3,000 | N/A | N/A | N/A |
| 7 | Perfect Circle Jv LTD | Unitedkingdom | Leicester | Halford House | Leicester | LE1 1HA | perfectcircle.***** | 2016 | $151,150,625 | 3 | N/A | N/A | N/A |
| 8 | Bladeroom Group LIMITED | Unitedkingdom | Churchdown Hill | Technology House | Gloucestershire | GL51 6TQ | bladeroom.***** | 2008 | $150,935,371 | 264 | N/A | N/A | N/A |
| 9 | Zaha Hadid LIMITED | Unitedkingdom | Finsbury | 101 Goswell Road | London | EC1V 7EZ | zaha-hadid-design.***** | 1999 | $97,584,439 | 502 | N/A | N/A | N/A |
| 10 | Gensler Europe, LTD | Unitedkingdom | London | Gensler Moretown | London | E1W 1YW | gensler.***** | 1965 | $93,581,858 | 318 | N/A | N/A | N/A |
| 11 | Grimshaw Architects Llp | Unitedkingdom | Finsbury | 57 Clerkenwell Road | London | EC1M 5NG | grimshaw.***** | 2007 | $92,145,558 | 466 | N/A | N/A | N/A |
| 12 | Deritend International LIMITED | Unitedkingdom | Leeds | 1 Park Row | Leeds, West Yorkshire | LS1 5AB | N/A | 1883 | $83,495,875 | 561 | N/A | N/A | N/A |
| 13 | M Moser Associates LIMITED | Unitedkingdom | Moorgate | Riverbank House | London | EC4R 3TN | N/A | 1999 | $68,052,764 | 117 | N/A | N/A | N/A |
| 14 | Foster + PARTNERS/WSP UK Joint Venture | Unitedkingdom | London | 3 Riverside Albert Wharf | London | SW11 4AN | fosterandpartners.***** | 2011 | $64,871,945 | 1,200 | N/A | N/A | N/A |
| 15 | Allford Hall Monaghan Morris LIMITED | Unitedkingdom | Clapton | 5-23 Old Street | London | EC1V 9HL | ahmm.***** | 1989 | $60,099,416 | 465 | N/A | N/A | N/A |
| 16 | Allies And Morrison Llp | Unitedkingdom | Rotherhithe | 85 Southwark Street | London | SE1 0HX | alliesandmorrison.***** | 1984 | $57,317,892 | 350 | N/A | N/A | N/A |
| 17 | Heatherwick Studio LIMITED | Unitedkingdom | Saint Giles | 55 Argyle Street | London | WC1H 8EE | heatherwick.***** | 2001 | $53,726,545 | 234 | N/A | N/A | N/A |
| 18 | A.C. Entertainment Technologies LIMITED | Unitedkingdom | Booker | Centauri House | Buckinghamshire | HP12 4HQ | ac-et.***** | 1982 | $50,163,918 | 211 | N/A | N/A | N/A |
| 19 | Benoy LIMITED | Unitedkingdom | Newark-on-trent | Handley House | Nottinghamshire | NG24 1EH | benoy.***** | 1947 | $50,041,872 | 422 | N/A | N/A | N/A |
| 20 | Ahr Management Services Llp | Unitedkingdom | Benchill | 5th Floor | Manchester, Greater Manchester | M2 4EW | N/A | 2014 | $47,466,257 | 258 | N/A | N/A | N/A |
| 21 | Hopkins Architects LIMITED | Unitedkingdom | Strand | 27 Broadley Terrace | London | NW1 6LG | hopkins.***** | 2019 | $45,051,341 | 186 | N/A | N/A | N/A |
| 22 | Hawkins Brown Architecture LIMITED | Unitedkingdom | Marylebone | Eastcastle House | London | W1W 8DH | hawkinsbrown.***** | 1988 | $44,832,582 | 318 | N/A | N/A | N/A |
| 23 | Wimberly Allison Tong & Goo (UK) LIMITED | Unitedkingdom | Saint Giles | Seven Dials Warehouse | London | WC2H 9LA | watg.***** | 1999 | $42,806,731 | 167 | N/A | N/A | N/A |
| 24 | Pascall + Watson LIMITED | Unitedkingdom | Moorgate | The Warehouses | London | EC4V 6ER | pascalls.***** | 1983 | $41,845,789 | 225 | N/A | N/A | N/A |
| 25 | Prp Group Llp | Unitedkingdom | Moorgate | 10 Lindsey Street | London | EC1A 9HP | prp-co.***** | 2019 | $40,924,823 | 309 | N/A | N/A | N/A |
| 26 | In House Design And Build LIMITED | Unitedkingdom | Oldland | 17 Noble Avenue | South Gloucestershire | BS30 8YY | inhousebuildingdesign.***** | 2013 | $40,232,924 | 57 | N/A | N/A | N/A |
| 27 | Ryder Architecture LIMITED | Unitedkingdom | Newcastle Upon Tyne | Coopers Studios | Newcastle Upon Tyne, Tyne and Wear | NE1 3NN | ryderarchitecture.***** | 1950 | $39,899,127 | 325 | N/A | N/A | N/A |
| 28 | Sheppard Robson Architects Llp | Unitedkingdom | Saint Johns Wood | 77 Parkway | London | NW1 7PU | sheppardrobson.***** | 1938 | $39,164,765 | 368 | N/A | N/A | N/A |
| 29 | Upp (reading I) LIMITED | Unitedkingdom | Moorgate | First Floor | London | EC4R 9AB | upp-ltd.***** | 2011 | $39,062,724 | 212 | N/A | N/A | N/A |
| 30 | Hawkins Brown Design LIMITED | Unitedkingdom | Marylebone | Eastcastle House | London | W1W 8DH | hawkinsbrown.***** | 2015 | $38,572,469 | 141 | N/A | N/A | N/A |
| 31 | Ips-Integrated Project Services LIMITED | Unitedkingdom | Chelmsley Wood | Unit 2300 | Solihull, West Midlands | B37 7YE | ipsdb.***** | 2013 | $38,311,326 | 138 | N/A | N/A | N/A |
| 32 | Chapman Taylor Llp | Unitedkingdom | Marylebone | 10 Eastbourne Terrace | London | W2 6LG | chapmantaylor.***** | 1995 | $37,322,031 | 299 | N/A | N/A | N/A |
| 33 | Corstorphine + Wright LIMITED | Unitedkingdom | Warwick | Brook Hall | Warwickshire | CV34 4BL | corstorphine-wright.***** | 1997 | $37,103,690 | 283 | N/A | N/A | N/A |
| 34 | Burns & Mcdonnell Europe (UK) LIMITED | Unitedkingdom | Canary Wharf | 5 Churchill Place | London | E14 5HU | N/A | 2015 | $35,912,047 | 175 | N/A | N/A | N/A |
| 35 | Kohn Pedersen Fox Associates (international) P.A. | Unitedkingdom | Saint Giles | Covden House | London | WC2H 9JA | kpf.***** | 1990 | $35,838,225 | 138 | N/A | N/A | N/A |
| 36 | Westonwilliamson+partners Llp | Unitedkingdom | Rotherhithe | 12 Valentine Place | London | SE1 8QH | westonwilliamson.***** | 1985 | $35,414,670 | 207 | N/A | N/A | N/A |
| 37 | Big Partners LIMITED | Unitedkingdom | Moorgate | 1 Finsbury Avenue | London | EC2M 2PF | N/A | 2016 | $35,320,802 | 162 | N/A | N/A | N/A |
| 38 | Pick Everard | Unitedkingdom | Leicester | Halford House | Leicester | LE1 1HA | pickeverard.***** | 2011 | $34,767,826 | 650 | N/A | N/A | N/A |
| 39 | Stride Treglown Group PLC | Unitedkingdom | Bristol | Promenade House | City of Bristol | BS8 3NE | stridetreglown.***** | 1990 | $34,223,124 | 333 | N/A | N/A | N/A |
| 40 | Stride Treglown LIMITED | Unitedkingdom | Bristol | Promenade House | City of Bristol | BS8 3NE | stridetreglown.***** | 1983 | $34,223,124 | 333 | N/A | N/A | N/A |
| 41 | Perkins + Will UK, LIMITED | Unitedkingdom | Moorgate | 150 Holborn | London | EC1N 2NS | perkinswill.***** | 2006 | $33,622,295 | 183 | N/A | N/A | N/A |
| 42 | Purcell Architecture LIMITED | Unitedkingdom | Bermondsey | Bermondsey Square | London | SE1 3UN | pmt.***** | 2018 | $33,468,974 | 287 | N/A | N/A | N/A |
| 43 | Ingleton Wood Llp | Unitedkingdom | Whitechapel | The Loom | London | E1 8PY | ingletonwood.***** | 1935 | $32,251,829 | 226 | N/A | N/A | N/A |
| 44 | Rshp Group LIMITED | Unitedkingdom | City of London | The Leadenhall Building | London | EC3V 4AB | lvgroup.***** | 1983 | $31,701,461 | 175 | N/A | N/A | N/A |
| 45 | Wilkinson Eyre Architects LIMITED | Unitedkingdom | Finsbury | 33-39 Bowling Green Lane | London | EC1R 0BJ | wilkinsoneyre.***** | 1999 | $31,045,350 | 181 | N/A | N/A | N/A |
| 46 | Ahr Architects LIMITED | Unitedkingdom | Benchill | 5th Floor Aurora | Manchester, Greater Manchester | M2 4EW | aedas.***** | 2002 | $30,445,782 | 182 | N/A | N/A | N/A |
| 47 | Impact Xm Europe LIMITED | Unitedkingdom | Leatherhead | Q2 | Surrey | KT22 7TW | touchassociates.***** | 2009 | $30,235,447 | 82 | N/A | N/A | N/A |
| 48 | Rshp Llp | Unitedkingdom | City of London | Level 14 | London | EC3V 4AB | rsh-p.***** | 2011 | $30,011,815 | 166 | N/A | N/A | N/A |
| 49 | Bryden Wood Technology LIMITED | Unitedkingdom | High Halden | Plurenden Manor | Kent | TN26 3JW | N/A | 2006 | $29,771,918 | 164 | N/A | N/A | N/A |
| 50 | Sheppard Robson People LIMITED | Unitedkingdom | Saint Johns Wood | 77 Parkway | London | NW1 7PU | sheppardrobson.***** | 2012 | $29,514,445 | 351 | N/A | N/A | N/A |
| 51 | Washroom-Washroom LIMITED | Unitedkingdom | Stapleford Abbotts | Hills Farm | Essex | RM4 1TU | washroom.***** | 2001 | $29,369,118 | 186 | N/A | N/A | N/A |
| 52 | John Mcaslan & Partners LIMITED | Unitedkingdom | Saint Johns Wood | 29-31 Saffron Hill | London | EC1N 8FH | mcaslan.***** | 1993 | $28,784,802 | 48 | N/A | N/A | N/A |
| 53 | Ibi Group (UK) LIMITED | Unitedkingdom | Benchill | Dantzic Building, Fourth Floor | Manchester, Greater Manchester | M4 2AL | ibigroup.***** | 1996 | $28,611,915 | 238 | N/A | N/A | N/A |
| 54 | Mcadam Design LIMITED | Unitedkingdom | Knock | Castlereagh Business Park | Belfast | BT5 6BQ | mcadamdesign.***** | 2012 | $28,409,832 | 152 | N/A | N/A | N/A |
| 55 | Epr Architects Group LIMITED | Unitedkingdom | Rotherhithe | Austral Street | London | SE11 4SJ | epr.***** | 2004 | $26,588,924 | 243 | N/A | N/A | N/A |
| 56 | Scott Brownrigg LIMITED | Unitedkingdom | Saint Giles | 77 Endell Street | London | WC2H 9DZ | scottbrownrigg.***** | 1910 | $26,170,563 | 169 | N/A | N/A | N/A |
| 57 | Epr Architects LIMITED | Unitedkingdom | Rotherhithe | Austral Street | London | SE11 4SJ | epr.***** | 1948 | $25,536,463 | 171 | N/A | N/A | N/A |
| 58 | Hta Design Llp | Unitedkingdom | Clapton | 75 Wallis Road | London | E9 5LN | hta.***** | 2013 | $24,786,513 | 224 | N/A | N/A | N/A |
| 59 | T P Bennett Services LIMITED | Unitedkingdom | Rotherhithe | 1 America Street | London | SE1 0NE | tpbennett.***** | 1993 | $24,655,420 | 320 | N/A | N/A | N/A |
| 60 | Broadway Malyan LIMITED | Unitedkingdom | Herne Hill | Holmes House | London | SE1 8BT | broadwaymalyan.***** | 1998 | $24,018,260 | 174 | N/A | N/A | N/A |
| 61 | Grimshaw Services LIMITED | Unitedkingdom | Finsbury | 57 Clerkenwell Road | London | EC1M 5NG | grimshaw.***** | 2007 | $23,371,337 | 216 | N/A | N/A | N/A |
| 62 | Adamson Associates (international) LIMITED | Unitedkingdom | London | 6th Floor, One Canada Square | London | E14 5AB | adamson-associates.***** | 1996 | $23,370,420 | 169 | N/A | N/A | N/A |
| 63 | Make LIMITED | Unitedkingdom | Marylebone | 32 Cleveland Street | London | W1T 4JY | makearchitects.***** | 2004 | $22,834,843 | 165 | N/A | N/A | N/A |
| 64 | Sheppard Robson LIMITED | Unitedkingdom | Saint Johns Wood | 77 Parkway | London | NW1 7PU | sheppardrobson.***** | 1996 | $22,592,714 | 14 | N/A | N/A | N/A |
| 65 | Precision Micro LIMITED | Unitedkingdom | Aston | 11 Vantage Way | Birmingham, West Midlands | B24 9GZ | precisionmicro.***** | 1983 | $22,569,101 | 155 | N/A | N/A | N/A |
| 66 | Crosher & James | Unitedkingdom | Saint Giles | Midcity Place | London | WC1V 6QS | N/A | 1935 | $22,525,897 | 450 | N/A | N/A | N/A |
| 67 | Fives Stein LIMITED | Unitedkingdom | Didcot | 4a Church Ward South Mead | Oxfordshire | OX11 7HB | fivesgroup.***** | 1993 | $22,150,396 | 60 | N/A | N/A | N/A |
| 68 | Hlmad LIMITED | Unitedkingdom | Whitechapel | 10-12 Alie Street | London | E1 8DE | architects-insurance.***** | 1964 | $21,715,225 | 205 | N/A | N/A | N/A |
| 69 | ADJAYE/ASSOCIATES LIMITED | Unitedkingdom | Strand | 223-231 Old Marylebone Road | London | NW1 5QT | adjaye.***** | 2000 | $21,374,610 | 85 | N/A | N/A | N/A |
| 70 | Boundary Visualisation LIMITED | Unitedkingdom | Saint Johns Wood | Academic House | London | NW1 7DJ | the-boundary.***** | 2014 | $21,064,763 | 146 | N/A | N/A | N/A |
| 71 | Plp Architecture International LTD | Unitedkingdom | Whitechapel | The Whitechapel Building | London | E1 8QS | plparchitecture.***** | 2013 | $20,773,234 | 134 | N/A | N/A | N/A |
| 72 | Claude Fenton (holdings) LIMITED | Unitedkingdom | Padworth | Kennet Weir Business Park | West Berkshire | RG7 4AE | claudefenton.***** | 1949 | $20,746,149 | 85 | N/A | N/A | N/A |
| 73 | Hok International LTD. | Unitedkingdom | Saint Giles | 90 Whitfield Street | London | W1T 4EZ | hok.***** | 1995 | $20,732,826 | 116 | N/A | N/A | N/A |
| 74 | Sybarite UK LIMITED | Unitedkingdom | Shepherd'S Bush | The Aircraft Factory | London | W6 0LE | syb.***** | 2002 | $20,718,752 | 90 | N/A | N/A | N/A |
| 75 | Buckley Gray Yeoman LIMITED | Unitedkingdom | Clapton | Studio 4/04 the Tea Building | London | E1 6JJ | buckleygrayyeoman.***** | 2000 | $20,063,434 | 143 | N/A | N/A | N/A |
| 76 | David Chipperfield Architects LIMITED. | Unitedkingdom | Moorgate | F I P P Ltd | London | EC2R 8EJ | davidchipperfield.***** | 1999 | $20,037,616 | 153 | N/A | N/A | N/A |
| 77 | The Hyphen Group LTD | Unitedkingdom | Otterbourne | 3 Charlecote Mews | Hampshire | SO23 8SR | hyphen.***** | 1999 | $19,868,120 | 167 | N/A | N/A | N/A |
| 78 | Kendall Kingscott LIMITED | Unitedkingdom | Bristol | Glentworth Court | City of Bristol | BS34 8SR | kendallkingscott.***** | 2002 | $19,696,429 | 192 | N/A | N/A | N/A |
| 79 | Pellings Llp | Unitedkingdom | Bromley | 24 Widmore Road | London | BR1 1RY | pellings.***** | 1990 | $19,660,214 | 190 | N/A | N/A | N/A |
| 80 | Arcadis UK Me LTD | Unitedkingdom | Saint Johns Wood | Black Bull Yard | London | EC1N 8JH | N/A | 2013 | $19,632,018 | 11 | N/A | N/A | N/A |
| 81 | Egis Road Operation M40 LIMITED | Unitedkingdom | Rotherhithe | 3 Valentine Place | London | SE1 8QH | N/A | 2018 | $19,288,653 | 113 | N/A | N/A | N/A |
| 82 | Feilden Clegg Bradley Studios Llp | Unitedkingdom | Bath | Bath Brewery | Bath and North East Somerset | BA1 7DE | fcbstudios.***** | 1979 | $19,101,683 | 181 | N/A | N/A | N/A |
| 83 | Eric Parry Architects LTD | Unitedkingdom | Finsbury | Discovery House | London | EC1Y 8QE | ericparryarchitects.***** | 1983 | $18,804,953 | 114 | N/A | N/A | N/A |
| 84 | Fulkers Llp | Unitedkingdom | Rotherhithe | 1 Long Lane | London | SE1 4PG | N/A | 2013 | $18,181,284 | 113 | N/A | N/A | N/A |
| 85 | Cegal LIMITED | Unitedkingdom | Esher | Two Furlongs | Surrey | KT10 9AA | cegal.***** | 2007 | $17,905,186 | 150 | N/A | N/A | N/A |
| 86 | Prp Architects Llp | Unitedkingdom | Moorgate | 10 Lindsey Street | London | EC1A 9HP | prp-co.***** | 1964 | $17,803,990 | 173 | N/A | N/A | N/A |
| 87 | Dar Al-Handasah Consultants (shair & Partners) (U.K.) LIMITED | Unitedkingdom | Moorgate | 150 Holborn | London | EC1N 2NS | dar.***** | 1975 | $17,632,148 | 100 | N/A | N/A | N/A |
| 88 | Thornsett Group LIMITED | Unitedkingdom | Finsbury | 34 Margery Street | London | WC1X 0JJ | thornsett.***** | 1989 | $17,043,674 | 19 | N/A | N/A | N/A |
| 89 | Adp Architecture LIMITED | Unitedkingdom | Herne Hill | The Fire Station | London | SE1 8SB | adp-architecture.***** | 2003 | $16,976,165 | 142 | N/A | N/A | N/A |
| 90 | Bond Bryan Architects (holdings) LIMITED | Unitedkingdom | Sheffield | 152 Rockingham Street | Sheffield, South Yorkshire | S1 4EB | bondbryan.***** | 2010 | $16,700,656 | 171 | N/A | N/A | N/A |
| 91 | Barker Associates (essex) LIMITED | Unitedkingdom | Black Notley | Majesty House, 200 Avenue West | Essex | CM77 7AA | barker-associates.***** | 2018 | $16,674,028 | 117 | N/A | N/A | N/A |
| 92 | Living Architecture Llp | Unitedkingdom | Mill Hill | 930 High Road | London | N12 9RT | N/A | 2006 | $16,505,581 | 18 | N/A | N/A | N/A |
| 93 | Zaha Hadid Holdings LIMITED | Unitedkingdom | Finsbury | Unit 11 | London | EC1V 0BD | zaha-hadid.***** | 1999 | $16,321,243 | 307 | N/A | N/A | N/A |
| 94 | Hawkins Brown Architects Llp | Unitedkingdom | Clapton | 14 East Bay Lane | London | E15 2GW | hawkinsbrown.***** | 2008 | $15,832,424 | 269 | N/A | N/A | N/A |
| 95 | The Harris Partnership LIMITED | Unitedkingdom | Wakefield | 2 St. Johns North | Wakefield, West Yorkshire | WF1 3QA | harrispartership.***** | 1984 | $15,507,852 | 168 | N/A | N/A | N/A |
| 96 | Crd Architecture Design Consultancy LIMITED | Unitedkingdom | Moorgate | 25 Farringdon Street | London | EC4A 4AB | callisonrtkl.***** | 1990 | $15,502,892 | 83 | N/A | N/A | N/A |
| 97 | Rmjm Scotland LIMITED | Unitedkingdom | Gorgie | 10 Bells Brae | City of Edinburgh | EH4 3BJ | rmjm.***** | 1956 | $15,494,926 | 122 | N/A | N/A | N/A |
| 98 | Stancold PLC | Unitedkingdom | Avonmouth | Portview Road | City of Bristol | BS11 9LQ | stancold.***** | 1946 | $15,118,769 | 118 | N/A | N/A | N/A |
| 99 | Bond Bryan Architects LIMITED | Unitedkingdom | Sheffield | 152 Rockingham Street | Sheffield, South Yorkshire | S1 4EB | bondbryan.***** | 1987 | $15,118,568 | 146 | N/A | N/A | N/A |
| 100 | Nightingale Architects LIMITED | Unitedkingdom | Benchill | Fourth Floor | Manchester, Greater Manchester | M4 2AL | N/A | 1989 | $15,083,888 | 282 | N/A | N/A | N/A |