Here are the results from Expert Flyer, on that date both TYO flights are scheduled to be on the B777.

Results from https://www.ExpertFlyer.comFlight Availability Search
Departing LHR on 22/02/18 0:00 for TYO
Flying BA
Direct/Non-Stop Only
Exclude Codeshares
Point of Sale: UK


Frequency
Flight Stops Depart Arrive Aircraft Reliability Available Classes
0 Connections
BA 7 0 LHR HND 777 Daily F9 A9 J9 C9 D9 R9 I9 W9 E9 T9 Y9 B9 H9 K9 M9 L9 V9 S9 N9 Q9 O9 G6
22/02/18 10:45 23/02/18 7:30 84% / 23m

0 Connections
BA 5 0 LHR NRT 777 Su,M,W,Th,F F8 A8 J9 C9 D9 R9 I9 W9 E9 T7 Y9 B9 H9 K9 M9 L9 V9 S9 N0 Q0 O0 G0
22/02/18 13:45 23/02/18 10:30 85% / 35m