Check this site out, its all about places nr London to hold corporate events and conferences by comp

Hedsor House is marvellous if you are searching for a stunning meeting and events venue set in an exclusive, private 100-acre estate. It is located high above the River Thames and is also quite close to Heathrow and London, making it ideal for many companies. The location is great for small team meetings right up to larger team building events,as well as an exclusive-use conference venue. Hedsor House is in Buckinghamshire and is an unforgettable place to meet, entertain or just relax and escape..