- Athco Gas
- Unit 113, Cannon Wkshps Cannon Dv, London, E14 4AS
- Avenue Supplies
- 020 89975071 - 15 The Avenue, London, W13 8JR
- C.g Gas
- 020 88026969 - 43 Grand Pde, London, London, N4 1AQ
- Roye Chapman Heating
- 0845 3473288 - 40 Fairlight Road, London, SW17 0JD
- Combi Services (heating) Ltd
- 020 88811941 - 196 Whittington Road, London, London, N22 8YL
- Domestic Energy Solutions
- 020 79163378 - 69 Cecil Rhodes Ho Goldington St, London, England, NW1 1UG
- Enfield Gas Appliances
- 020 88030405 - 47 Westerham Avenue, London, N9 9BP
- G A Services
- 020 74762746 - 99 Cumberland Road, London, E13 8LH
- Gas Services Group
- 020 84715510 - 4 Thorngrove Road, London, E13 0SJ
- Gasline
- 020 88821919 - 86 High Rd, London, N17 9SZ
- Harrys Gas Appliances
- 020 86796868 - 1577 London Road, London, SW16 4AA
- South London Gas Appliances
- 020 86933444 - 344 Lordship Lane, London, SE22 8LZ
- Lordship Cooker Centre
- 020 88894350 - 445 Lordship Lane, London, N22 5DJ
- J.O Mullarkey
- 020 86978850 - Lock Ups The, 3 Braidwood Road, London, SE6 1QU
- N & C Services
- 020 82917948 - 57 Vancouver Rd, London South-east, SE23 2AH
- Neasden Gas Appliances
- 020 84506546 - 566 North Circular Road, London, NW2 7QA
- Power Service, The
- 020 86760543 - 217 Sydenham Road, London, SE26 5HF
- Regal Gas Services
- 020 79233222 - 18 Ashwin St, London East, E8 3DL
- Saunders Gas Services
- 020 79240723 - 83a Landor Road, London, SW9 9RT
- Saunders Stores
- 020 77334772 - 83a Landor Road, London, SW9 9RT
- Seaflame
- 020 72313944 - Millender Walk, London, SE16 2BJ
- Sovereign Gas
- 020 83469392 - 18a Dollis Park, London, N3 1HN
- Walthamstow Gas
- 020 85207005 - 51 Wood Street, London, E17 3JX
- Wandsworth Gas
- 07711 750978 - 98-100 Putney Bridge Road, London, SW18 1NJ
- Academy Maintenance Group
- 020 85079584 - 77 Fanshawe Avenue, Barking, Essex, IG11 8RF
- B.J.L.
- 01708 458699 - 264 Southend Arterial Road, Hornchurch, Essex, RM11 2SQ
- C.J Cross
- 020 83668390 - 165 Great Cambridge Road, Enfield, Middlesex, EN1 1SG
- Allen J Fether
- 020 83632366 - 12 St. Johns Terrace, Enfield, Middlesex, EN2 9AQ
- T.A Horn
- 020 84408811 - Enterprise Ho St.Wilfreds Rd, Barnet, Hertfordshire, EN4 9SA
- Gas Appliances
- 020 88949929 - 18 High Street, Whitton, Twickenham, Middlesex, TW2 7LT
- Gas Tec
- 020 88420939 - 1a Station Parade, Ealing Road, Northolt, Middlesex, UB5 5HR
- Avon Ruby (uk) Ltd
- 020 85751336 - Avon Ho Ferrymead Gdns, Greenford, Middlesex, UB6 9NE
- Swift Gas Services
- 020 84223727 - 312 Eastcote Lane, Harrow, Middlesex, HA2 9AH
- Bickley Gas Services
- 020 84678070 - 185 Southborough Lane, Bromley, Kent, BR2 8AR
- Dolphin Domestic
- 020 86801904 - Cotswold Dering Pl, Croydon, Surrey, CR0 1DT
- Gas Homes
- 020 86860131 - 96 Church Street, Croydon, Surrey, CR0 1RD
- Ruffin Engineering Services
- 020 83353867 - The Metro Cntr Garth Rd, Morden, Surrey, SM4 4NJ
- Seaflame
- 020 83306055 - 839 London Road, Sutton, Surrey, SM3 9BJ
- South London Gas Services
- 020 83942252 - 200 Banstead Road, Banstead, Surrey, SM7 1QG
- Boiler Team
- 07903 935886 - 15 Parkview, Wembley, Middlesex, HA9 6JZ
- Bromley Gas Service
- 020 84629706 - 4 Malling Way, Bromley, Kent, BR2 7PJ
- Blaze Heating
- 020 31493488 - 75 Milborough Crescent, Lee, London, SE12 0RP
- E.o.r Bioler & Heating Engineers
- 01708 750777 - The Seedbed Cntr Davidson Wy, Romford, Essex, RM7 0AZ
- Merit Gas & Heating
- 020 82009739 - 164 Booth Road, London, NW9 5JZ
- M K Gas Services
- 020 88864114 - 482 Green Lanes, London, N13 5PA
- Exoteric Ho
- 020 89044422 - 11 Osram Road, East Lane, Wembley, Middlesex, HA9 7NG
- Chaucer Gas
- 020 86432290 - 34 Langley Park Road Sutton, Surrey, SM2 5HF
- Pargas
- 020 83641605 - 11 Queen Annes Place, Enfield, Middlesex, EN1 2QB
- Charles Grey
- 07703 533703 - 27 Alton Road, Richmond, Surrey, TW9 1UJ
- Heatwave Engineering
- 020 79245000 - 152 Kings Avenue, London, SW12 0BA
- Heatwave Engineering
- 020 79245000 - 152 Kings Avenue, London, London, SW12 0BA
- Gas Mark 1
- 020 79162007 - 81B Messina Avenue West Hampstead, London, NW6 4LG
- M J Hayes Plumbing and Heating
- 020 88412527 - 49 The Fairway, Ruislip, Middlesex, HA4 0SP
- M J Hayes Plumbing and Heating
- 020 88412527 - 49 The Fairway, Ruislip, Middlesex, HA4 0SP
- Main
- 020 88093414 - 10 Overbury Road, London, N15 6RH
- Gas Mark 1
- 020 79162007 - 81B Messina Avenue West Hampstead, London, NW6 4LG
- Exoteric Gas Solutions
- 020 89082777 - Osram Rd East La, Wembley, HA9 7NG
- O P Services
- 07973 110042 - 67 Colombo Road, Ilford, Essex, IG1 4RH
- Precision Gas & Plumbing
- 01708 706853 - 29 Drummond Road, Romford, Essex, RM7 7EJ
- Central Gas Ltd
- 020 86961290 - 51a Bennerley Road, Battersea, London, SW11 6DR
- London Plumb Ltd
- 0845 0579344 - 27 Old Gloucester Street, London, London, WC1N 3AF
- S Gillam
- 020 84197008 - 19 Dennett Road, Croydon, Surrey, CR0 3JD
- Athco Gas
- 020 72522100 - Kirby Est Southwark Pk Rd, SE16, SE16 2EF
- Tics
- 020 85779425 - TW3 3UQ
- Intersmooth Ltd
- 0800 0329981 - 1 Park View Road Apartment 6, London
- JDR Reactive Ltd
- 020 77249361 - 31 Harcourt Street, London
- Gas Emergency
- 07950 217890 - 22 Notting Hill Gate, London, London, W11 3JE
- Heating & Boiler Engineers A Brassett
- 020 84626073 - 10 Addington Road, West Wickham, Surrey, BR4 9BS
- Sidcup Plumbing & Heating
- 020 83003354 - 1 Studland Close, Sidcup, Kent, DA15 7HP
- Ongas
- 020 71832284 - 6 Regency Court, South Woodford, London, E18 2JT
- Pro-tec Bs Ltd
- 07919 830947 - 18 Chipstead Garden Dollis Hill, London, England, NW2 6EL
- Radmasters Services Ltd
- 020 83359123 - 131 Caldbeck Avenue, Worcesters Park, Surrey, KT4 8BJ
- Amber Plumbing & Heating
- 020 82489389 - 9 North Avenue, Harrow, Middlesex, HA2 7AE
- The London Gasworks
- 0845 6432510 - 27 Old Gloucester Street, London, London, WC1N 3XX
- Spark Gas Installations
- 0845 5433900 - 2a Erconwald Street, London, W12 0BS
- SM1 Services
- 0845 5433198 - 9 Westmead Road, Sutton, Surrey, SM1 4JT
- Djc Plumbing & Heating Services
- 0800 9558387 - 19 Chevington Way, Hornchurch, Essex, RM12 6RW
- Bradco Gas Services
- 020 82391078 - 21 Beverley Road, Worcester Park, Surrey, KT4 8LX
- Nhl Gas Services
- 01708 721254 - 73 Redriff Road, Romford, Essex, RM7 8HD
- Jason Watson
- 49 Queensbridge Court, London, Hackney, E2 8PQ
- Nicks Plumbing and Heating
- 0845 1364034 - 42 The Sunny Road, Enfield, EN3 5EE