mtravelkay wrote:
Even at 1 percent for credit cards, it would seem that for most tickets
bought on Expedia, it would be cheaper for them to pay the 45p debit
carc fee. A 100 GBP ticket would result in a 1-4 GBP charge for credit
cards, and only a 45p charge for debit cards.

Real debit cards are not usable on internet. Requires physical presence of
card and entry of PIN, since they enable ATM like transactions live on your
accounts. (and on those of merchant).
Merchant could capture your card number and PIN, magnetically encode a card
and then go to the nearest ATM and perform any transaction you can perform.