The pub name refers to the flasks of Hampstead spring water that were distributed
to wealthier Londoners at a time when a guaranteed clean water supply was highly
valued. The original Flask Tavern on the site was home to the Hampstead mineral water
business from about 1700 and lasted 50 years.
The current building retains the Victorian mahogany and glass partitions, plus the
original cast-iron fireplaces with tile surrounds.