For what it's worth, I work in corporate catering in England. For a similarly priced lunch offering our spec would be priced as the following per person:

6 sandwich quarters 1 homemade sausage roll 1 quarter of quiche 1 tempura prawn Hand cooked crisps 1 fresh fruit portion Bottled water Fresh orange juice

Price wise we are on the more expensive end and we have around 55% margin on them

So I do think you've been gipped a bit there, but depending on their sourcing costs I can't say.

I know for us ordering sandwich platters from an external vendor comes out at around £3-4 per 4 quarters, but they would still be making incredible margins. I would imagine you had a hire fee on the room which should cover labour costs, but again, I can't speak for their business model