Anyone have any experience of spas in and around London ?

Big sister’s birthday on the horizon, and would like to get her a spa day but the places in London look horrendous, the kind of places where hatchet faced silicon enhanced beauticians would look sniffily at anyone who carries a bit of extra timber. I’m thinking old fashioned relaxing place, old world courtesy where a chap is a chap and a lady is a lady. She has more than enough to deal with at work, so doesn’t need any attitude, and a bit of relaxation would do her some good.

I know of Grayshott Hall which looks like it might fit the bill, but any other suggestions are most welcome. She has family in the Lakes so even a get-away up there is a possibility.

Many thanks.