I've been to Stadhampton and I would say... don't.
For the price you pay, there are MUCH better hotels out there. Our room was really dark, there were no bedside lights, which made reading impossible and the bathroom was completely open plan, including the loo. And the so-called infinity bath was rubbish. And the shower floor was really slippery. And the lights in the bath made DH's willy go green, which was funny but not romantic.
It might be a great place to go if you're shagging your secretary and don't plan to have a poo while you're away, but if you want to (a) read the paper and (b) poo in private, don't do it. DH made me stand outside the hotel room door in my dressing gown and that is NOT COOL. The pub and restaurant were lovely, but a lot of the rooms at Stadhampton are in a separate building which is round a bend off quite a main road and very dark and miserable if it's raining (take a torch, you will really need it).
If you're having an affair, or are in the lust-fuelled throes of a new relationship, just need the room for one night and have superb sphincter control by all means indulge.
For the same money, I'd go to one of the Firmdale hotels in London any time. Or if London doesn't float your boat, The Residence in Bath. Or Babington, or Cowley Manor.
The Crazy Bear restaurant in London (same owners) is great, but the hotels just don't do it for me at all.