I copied this info from a book on Tea Rooms the last time we were in England (May 2000):

Chipping Camden (Cotswolds): Forbes Brasserie (Cotswold House), High St.
Bath: The Canary Restaurant
Ambleside (Lakes District): Sheila's Cottage
Ullswater (Lakes District): Sharrow Bay Country House Hotel
Marlborough: Polly Tea Room
Kenilworth: Time for Tea
Tiverton: Canal Tea Garden

From this list we only went to the one in Marlborough, but it was good.

Pauline from Slow Travelers

The presence of Sharrow Bay (a lovely but very expensive hotel/restaurant in the Lake District) amongst a list of tea rooms prompted me to pass on a tip about London hotels. The famous names like the Dorchester, the Hyde Park, etc, are astonishingly expensive to stay in or have dinner there. But they all do afternoon teas for non-residents: it allows you to experience the service and ambience of these extraordinary establishments for a fraction of the cost.

Jonathan