Ideas for Mum's 70th afternoon tea in London

[AnnieHoo]

I want to spoil my mum for her 70th birthday weekend so we are booked to go to London. I'd love to stay in a boutique hotel with her, have afternoon tea together somewhere fancy but not stuffy and then on the Saturday go for lunch with family by the river (young kids age 5-7 so not too posh). Any ideas? Covent Garden hotel looks gorgeous.

I found national (portrait?) gallery afternoon tea interesting. Might be a bit loud though

OXO tower is good for informal dining on the river and a bit special

I'm pretty sure that the Brasserie in the OXO tower has a kids menu.
I take my mum for afternoon tea on her birthday every year. Fortnum and Mason do a nice one which isn't pretentious. You can have a private tea tasting for an extra £10. When we went to see Charlie and the Chocolate Factory at the West End we had a Charlie and the Chocolate Factory themed afternoon tea. My Mum loved it! For her big 60, to make it a bit special we went to an afternoon tea workshop in London where we made a selection of treats and then we were served a nice cup of tea while we eating them.
We once had tea at the Royal Opera House after a behind the scenes tour. We got to see the set being made, the costume depeartment and ballet dancers rehearsing. It was a very interesting tour.