That's what I'm saying. I like Pret; it was the poster alanR who said if one pays Pret prices, "someone saw you coming." But when your small boy wants two or three at a go, plus Limonata, one is soon, as they say, talking real money.

Back to the OP's concerns (and I hope he shows up again to read all this)... I stand by my recommendation that US$50 / day is fair "sidewalk money" for London. Especially considering that the girl may want to do touristy things like go up the Eye, ride that open-topped sightseeing bus around town, visit M Tussaud's, etc. All these things are more expensive than Americans might anticipate.