Yesterday DP and I had food and drinks in a local fish and chips place. Both food and service were ok: not remarkable, but perfectly acceptable. Bill came to £19.20. We put £22 on the plate. A couple of minutes later, as we were finishing our drinks, the waitress returned £1 to us on the plate. DP was really embarrassed, saying we can't have tipped her enough. I maintain that £2.80 (c. 14%) was a reasonable tip.
Was the waitress just making a point by returning £1 to us? (Please note that she did not return the whole tip of £2.80.) Or was ours a reasonable tip for reasonable food/service?