The George Hotel is a hotel in Wallingford in Oxfordshire. The hotel is located on the same street as The Lamb.
In the novel Dumb Witness, Poirot and Hastings visit Market Basing which is believed to be a town inspired by Wallingford. They lunch at an inn called The George. It is possible that Christie had the actual George Hotel in mind, but her notebooks indicate that she was probably thinking about another inn just two blocks away on the same street called The Lamb. See the discussion here.
The George Hotel at Wallingford.