It's interesting (to me, at least) to see the kinds of discounts that folk apply to gift card transactions. It's not unheard of for a colleague to end up with a gift card they can't use, and while there's a real sense in which the card is worth its face value, there's also a sense in which its restricted use makes it worth less than face value. Plus, if you want to spend £x in a shop then you don't normally need to buy a colleague's gift card.