[3] Congreve's design used two water-filled caissons, which were moved up and down by hand, assisted by compressed air trapped beneath the tanks.

With no working examples of such lifts, the directors were understandably cautious, but following an engineer's report, decided that Maudslay & Co should build a prototype at Camden Town.

Congreve's claim that it could be operated in just three minutes was never proved, and in 1818, the directors decided to cut their losses, and reverted to using paired locks.

[7] The transfer of water between the chambers made operation of the locks more complex, and so they were permanently manned during the heyday of the canal, with lock-keepers working a shift system to provide 24-hour cover.

As the use of the canal declined, in part due to railway competition, manning levels were reduced, and padlocks were used to prevent operation of the locks at the weekends.

The cost was met by the St Pancras Vestry and the Metropolitan Board of Works, and the bridge, which has brick abutments with stone coping, carries a plaque recording this fact.

[10] At the south-east corner of the lock is a building dating from 1815, which was originally constructed to house air compressors for Congreve's boat lift.

[12] The towpath is on the northern bank of the canal at this point, and is carried over the entrance to a dock which formed part of Camden Goods Depot by a cast iron single span bridge with stone capped abutments.

Robert Stephenson was the engineer in charge of the project, and he picked the site for the goods depot so that direct interchange with the Regent's Canal was available, from where freight could reach the London docks.

A Western Horse Tunnel was also built to link the goods depot to new stables near the present Gloucester Avenue, to the west of the mainline tracks.

[14] Despite some demolition, the complex of buildings, which includes parts of the goods depot, the winding engine house, the Roundhouse, the eastern portal of Primrose Hill railway tunnel, and the canal, represent one of the most important groupings of 19th-century transport infrastructure to have survived in Britain.

The area around Hampstead Road Locks was populated by disused warehouses, derelict land and a towpath which desperately needed some repairs to be made.

In addition, the area was blighted by the proposed London Motorway Box, which would have seen much of the canal culverted, and a sliproad built over the site of the locks.

[17] The lease was bought by Northside Developments, a limited company which had been formed by Bill Fulford and Peter Wheeler, and had previously been involved in turning large houses into flats in south London.

The plans included workshops, restaurants, sculpture studios, a snack bar, a mooring area for canal boats, and an office.

[20] An official opening was held on 4 April 1973, with the Mayor of Camden presiding, and this was followed by a three-day display of work by the fifty people who were by then occupying the workshops.

Northside then obtained a development lease, but applications to demolish and replace many of the buildings were successfully resisted by a tenants' association, formed by the craft workers.

It featured live music, and in order to stay open until 2am, the terms of the licence required an entrance fee to be charged, which was set at 50 pence by the licensing authority.

[24] Regular customers included David Hockney, Lucian Freud and George Melly, and it soon became well known as a venue for punk rock bands.

The towpath from London Zoo to Camden High Street was then opened for public access, following a campaign by the Regent's Canal Group.

Despite objections from the fire brigade, the Greater London Council eventually sanctioned the name change, and from then on, the site was marketed as Camden Lock.

[31] British Rail carried out repairs to the railway bridge over Chalk Farm Road in the mid-1980s, and when the work was completed, the hoardings were not replaced.

A four-storey building was erected, fronting Chalk Farm Road, and the space between it and Dingwalls, which had been the site of the original market in the 1970s, was covered by a glazed cast iron and brick structure the designs for which were based on a Victorian gas showroom.

Despite the increased timescales and costs of doing so, Northside attempted to redevelop the East Yard without closing the market, in order to retain its vibrancy.

It is a busy market which attracts many visitors, and with music venues, cafes and canal towpath walks, it has become one of London's most popular tourist destinations.

[40] There are a number of art installations in the area,[41] including a large cut-steel sculpture by English artist Edward Dutkiewicz in the square beside the lock.