The British Airways fleet of 777s is quite finely diced into several configurations, although as far as the Heathrow based aircraft are concerned, there is movement towards consolidating the fleet into three types through a programme of fleet refurbishments.  At the beginning of 2023, the Heathrow fleet comprises of three dominant types: the three class 200ER (77L), the four class 200ER (77M), and the four class 300ER (77H).  There are six 77Gs in active service which are expected to be converted to the 77H type in 2023 plus three 77Rs (LGW spec) also operating out of Heathrow

The London Gatwick fleet is fitted out in two separate cabin configurations: 77S and 77T

If you need any assistance pin-pointing the correct 777 type, there are several tips you can follow in our BA 777 Cabin Layout Recognition article

Current breakdown:

Four class Boeing 777-200ER
Type 77M
G-RAES G-VIIA G-VIIB G-VIIC G-VIID G-VIIE G-VIIF G-VIIG G-VIIH G-VIIJ G-VIIK G-VIIL G-VIIM G-VIIN G-VIIS (15)
Refreshed 2010 First, 2019 CWS, 2010 WT+, 2018 WT (10 abreast) and Thales IFE

Type 77R
G-VIIV G-VIIW G-VIIY (3)
2010 First, 2006 CW, 2018 WT+, 2018 WT (10 abreast) and Panasonic ex3 IFE

Four class 777-300ER
Type 77G
G-STBA G-STBB G-STBC G-STBE G-STBF G-STBI (6)
2010 First, 2006 CW, 2010 WT+, 2010 WT (9 abreast) and Thales IFE

Type 77H
G-STBD G-STBG G-STBH G-STBJ G-STBK G-STBL G-STBM G-STBN G-STBO G-STBP (10)
2020 First, 2019 CWS, 2018 WT+, 2018 WT (10 abreast) and Panasonic eX3 IFE

Three class 777-200ER
Type 77L
G-YMMG G-YMMH G-YMMI G-YMMJ G-YMMK G-YMML G-YMMN G-YMMO G-YMMP G-YMMR G-YMMS G-YMMT (12) with the conversion of G-YMMU (no 13) in progress as at 1 April 2023
2019 CWS, 2018 WT+, 2018 WT (10 abreast) and Panasonic ex3 IFE

Type 77S
G-YMMA G-YMMB G-YMMC G-YMMD G-YMME G-YMMF (6)
2006 CW, 2018 WT+, 2018 WT (10 abreast) and Panasonic ex3 IFE

Type 77T
G-VIIO G-VIIP G-VIIR G-VIIT G-VIIU G-VIIX (6)
2006 CW, 2018 WT+, 2018 WT (10 abreast) and Panasonic ex3 IFE