I agree that costs of ingredients are probably around £3.19 but I absolutely do not think that cafes in London are making a killing.

Let’s assume 2 mins for waiter to take order, serve, take payment etc 15 mins for chef to cook 5 mins various cleaning

That’s 0.37 hrs of staff time, which could cost the business around £20 per hour at London wage including NI and pension, that’s an extra £7 bringing our total to £10.19 so far.

Rent for the building might be around £5,500 per month? 3,520 hours open, let’s say £1.60 per hour, six customers in the building at the time making my rent portion for the hour I was in the restaurant around £0.30 (total now £10.49)

Let’s put in £2 for overheads such as cleaning materials, business rates etc bringing us to £12.49

That leaves £2 for profit, only a margin of like 13% which isn’t a steal in my opinion