But Heaton wasn't having it:
@wellesleylondon - still no apology though and no refund. I will let others decide what that says about your attitude to customers...
— Edward Heaton (@EdwardHeaton) July 23, 2014 The Wellesley responded in a public statement:
"Mr Heaton did not raise concern at the time of his visit but did send an e-mail of complaint the following week. In response, The Wellesley’s management team replied on the same day to offer its sincere apologies to Mr Heaton for an experience he deemed less than satisfactory".
But Heaton, who said he "wasn’t angry", admitted his real problem was with the sneaky hidden charge.
“I have no issue if they have a minimum charge, but they need to make it clear. It is the lack of transparency that I have a problem with".
The hotel stridently defended its policy, saying “Guests are made aware of this policy on arrival and the rates are printed on the menus distributed on the terraces", adding that “the minimum spend... is comparable to similar venues across London".
Heaton, a regular at upmarket hotels in the already expensive city, insists he has "never had this before" and "will never set foot in that hotel again".
If he does, though, he'll no doubt order something stronger than water to make sure he gets his money's worth.
Chloe Pantazi is an editorial assistant on Thrillist's travel team. Yes, that's a British accent. No, she doesn't watch Doctor Who. Follow her on Twitter at @ChloePantazi.