Marston's has sold the Swan at Ascott-under-Wychwood, Oxfordshire, from the El-dridge Pope estate it acquired in January.
The business has been bought by Richard Lait from Gloucestershire. Lait has been working in the building trade for the last 30 years, but before that, ran a wine bar in London.
The pub is to be closed for a comprehensive refurbishment and a 2008 re-launch as a quality dining pub with luxury bedrooms.
Peter Brunt, of Colliers Robert Barry, which handled the sale, said: "Having acquired Eldridge Pope, Marston's decided that the Swan was surplus to its requirements. We managed to generate huge interest, something we are finding regularly with Cotswold pubs this year. This is a great pub and it's got the potential to be one of the top, food-led businesses in the Cotswolds."
The freehold sold off an asking price of £525,000.
Lait said: "This beautiful old pub is in an incrediblly sought-after area, but it's suffered a serious lack of investment over the last 30 years ago and was only turning over £50,000 with Marston's.
"The pub was in a very poor state when I came in. The kitchen had been shut for two years. We plan to renovate the whole place - I've organised and designed everything myself. I've got one full-time guy with me and we'll get in sub-contractors. I don't think I'll get much change out of £1 million for this project. When we reopen in spring, we hope to be turning over at least £500,000."
Stephen Taylor, of Guy Simmonds, said: "It's a great place to own a pub, possibly the best in the country. It's a highly affluent area, particularly popular with people from the south."