The Mitre at Hampton Court is a Grade II listed riverside hotel dating from the 17th century, originally built to house overflow guests from Hampton Court Palace and now run as a characterful boutique property with 36 rooms. the rooms look over the Thames!
It is believed it was built in 1665 under Charles II as ancillary accommodation for palace guests, and later rebuilt in the mid‑18th century; it is now Grade II listed.
 
Interesting facts...
Originally the site was occupied by a tavern called 'The Toy'. The inn became a meeting place of the Toy Club presided over by the future William IV, and there are longstanding stories of secret tunnels linking it to the palace.