That's assuming everyone takes the full 10kgs. Just booked the missus and I GLA-SOU (that is Southampton, isn't it? I normally deal with ICAO designators...). Just going for a couple of days so could probably have got away with a couple of 10kg hand bags but decided to pay an extra four quid to take one hold bag both ways. Decided we couldn't be arsed lugging everything into the overhead lockers of the 146/DH8 or whatever the equipment is.
Fare came to about £47 each return including the bag and credit card fees. Still a good fare, even if the original quoted fare was 88p each way
Decided not to pay the extra to pre-select the seats...