Horwood House - secret agent training school!

I've started writing the sequel to The Secret of Saynshand, in which my heroine, Li Bic, is sent for training as a secret agent.
She arrives in England, in proper Steampunk fashion, aboard an airship, which lands at Northolt Aerodrome. This was the predecessor to Heathrow.
I knew I wanted the training school to be a country house somewhere in Southern England, but where?
So I had a look at a railway map - and found the line going to Bletchley. Bletchley Park, as a code breaking institution, didn't exist in 1895, of course, and neither did nearby Milton Keynes, but one of the villages close by might fit the bill for my purposes.
Great Horwood sounded as if it was the sort of place that would have a Hall.
So I looked it up - the house is actually called Horwood House, and seems to be a hotel where they do weddings now - and it is absolutely perfect as a setting!