This Nag's Head (not to be confused with the more renowned one at 10 James St.) is on a back street a short walk from the Berkeley Hotel. Previously a jail dating from 1780, it's said to be the smallest pub in London. In 1921, it was sold for £12 and 6p. Have a drink up front or wander to the tiny bar in the rear. For food, you might enjoy "real ale sausage" (made with pork and ale), shepherd's pie, or the quiche of the day, all served by the welcoming staff. A cosmopolitan clientele -- newspaper people, musicians, and travelers -- patronizes this warm, cozy pub. This pub touts itself as an "independent," or able to serve any "real ale" they choose because of their lack of affiliation.