Originally Posted by
ISTFlyer
Yes, ask for one at check-in as the agents could assign them or alternatively, pay for them in advance if the system allows.
Thanks ISTFlyer, didn't pay for the seat as the system wanted $158, but after being 'auto-assigned' something like 48B (was on cheapo-fly ticket with no seat selection) went to checkin desk at LHR for my connecting flights, asked nicely and got 8D. [that's for a non-TK *G]