Well, thanks 419 That does answer the question.
If BA can sell the item for £69 then that is all fair and good. The individual in question decided not to investigate the details and then decided to pay the asked price and have the unit to use again. It may be that I have travelled more than some (but less than others) but airliners do not supply 110/220 AC for pax use as standard, whereas trains often do.
True that the BA did not inform the prospective pax of the detail but we do not know how the question was phrased and if by email or phone, whether direct to BA or through an agent. On this occasion I feel sorry for BA who have been pilloried beyond what is involved.