Speaking about the British Airways Boeing 777 fleet exclusively, there are four different seat maps for the aircraft: 777-200ER with first class, 777-200ER based at LGW, 777-200ER, and 777-300.

Boeing 777-200 and 777-300, and the Boeing 787-9 and 787-10. The aircraft are configured as follows, with 331 seats across three cabins (based on data from seatguru.com): Importantly, the A350-1000 is ...