Originally Posted by G-BOAC
BA don't do this ex-LON.
However for ex LHR flights, you could check with the CSD for onboard upgrades from WT+ to Club as well. The answer will be dependant on the meals onboard as well. They will not serve you a WT+ meal in the club cabin.
There was a list of charges posted in the past (
Spottie?), but somehow £600 for a one-way onboard WT+ -> Club upgrade seems to ring a bell...