At the beginning of the 18th century, the hills of Hampstead had a resource which was becoming increasingly precious.clean drinking water. London was expanding at a furious rate and its fresh water supply was overstretched and polluted.

The water was collected from the natural springs and taken to a village pub, known as the Thatched House, where it was bottled and sold at threepence a flask. It was also sold to the taverns and coffee houses of London. Soon it acquired dubious medicinal qualities, relieving "complaints..of idleness, dissipation and frivolity".

Gradually the open countryside between London and its surrounding villages was built upon. In 1874, the Thatched House was demolished and replaced by the Flask, a workaday Victorian pub in a working class area. Today the workers' cottages fetch unbelievable sums.

The Flask is a friendly and welcoming pub. There are two bars at the front which are separated by a beautiful glazed partition which was added in the 1880's. On the saloon bar side are panels painted by Jan Van Beers. This bar is a little more comfortable and has a fine cast iron fireplace. At the rear is the conservatory and dining room.