BA Booking Fee £4.50 per ticket but depends on the country as its $30 per ticket if in Israel.
BA's booking fee for tickets bought online - Times Online
Mind you BA was 1st to impose hits on people who booked online 5 years ago.
Then again Fingleton made no comment on BA charging £15 to reserve a seat or seems unwilling to force airlines to include the Fuel surcharges which they have been imposing for almost 2 years into their advertised ticket price.