Brent Reservoir
The Brent Reservoir (popularly called the Welsh Harp) is a reservoir which straddles the boundary between the London boroughs of Brent and Barnet and is owned by British Waterways. The reservoir takes its informal name from a public house called The Welsh Harp, which stood nearby until the early 1970s. The reservoir is fed by the Silk Stream and the River Brent, and its outflow is the River Brent. It is said to contain enough water to fill 3 million baths, and in 1994 when the reservoir was drained over 6,700 lb (3,000 kg) of fish were captured, 95% of which were Roach. However, fishing is prohibited. The reservoir is also a sailing centre, home to BTYC Sailsports, Wembley Sailing club, Seahorse Sailing Club, the Sea Scouts, and the University of London Sailing club.

Construction of the reservoir
Plans for the construction laid in 1803 were abandoned because of cost. However canals continued to develop in the early 19th century and there were water supply problems. By 1820 there was not enough water to supply the Grand Union Canal and the Regent's Canal so under an Act of Parliament in 1819, the Regent's Canal Company decided to dam the River Brent and create a reservoir. The reservoir was constructed by William Hoof between 1834 and 1835. The water flooded much of Cockman’s Farm, to supply the Regent's Canal at Paddington. It was called Kingsbury Reservoir and its 69 acres (280,000 m 2) spread between Old Kingsbury Church and Edgware Road. Hoof, who was awarded the tender for the work (including the construction of a bridge) received the sum of £2,740 and six shillings. Construction did not proceed without problems; in August 1835, a few months before completion, four brothers named Sidebottom drowned in an accident. Additional building was completed in December 1837 to extend the reservoir. In 1841 after seven days of continuous rain the dam head collapsed, killing two people. It was after this that a supervisor was employed for the first time, with a cottage near the dam. This cottage still exists. At its greatest extent it covered 400 acres (1.6 km²) in 1853, but was reduced to 195 acres (789,000 m²) in the 1890s, and subsequently reduced to 110 acres (445,000 m²).

During the second half of the 19th century the area became a destination for recreation and evening entertainment, almost entirely due to W.P. Warner (1832”“1899), who in 1858 became licensee of the Old Welsh Harp Tavern. The tavern stood on the Edgware Road, near where it crossed the Brent. Warner, who fought with distinction in the Crimean War, created the tavern along the lines of the London Pleasure gardens (ironically at the same time when the most famous of all, the Vauxhall finally closed). For 40 years, Warner made the Old Welsh Harp Tavern one of London's most popular places and it was celebrated in song by the music hall star Annie Adams as 'The Jolliest Place That's Out'. The amusements were focused not just on the inn, but around the reservoir. Warner operated a race track until an Act of Parliament made it illegal. The first greyhound races with mechanical hares took place here in 1876. In 1891, there was an attempt by Capazza to launch his Patent Parachute Balloon, which failed to leave the ground. Accounts record 'nasty incidents' among the 5000 spectators. These activities attracted a mixed clientele and crime and violence was not uncommon. One observer described the races as a 'carnival of vice'. The reservoir, like nearby Hampstead Heath, was also famous for Bank Holiday fairs. There was an incident during its Victorian heyday when a bear escaped from the menagerie. The first formal cycle race was held at the Welsh Harp on 1 June 1868 . It was won by Arthur Markham. He received a silver cup from the licensee of the Welsh Harp Hotel, who had sponsored the race. For many years Markham had a bicycle shop at nearby 345 Edgware Road. The race was held the day after what is often referred to as the world's first race, in the park at St Cloud west of Paris. It was won by another Englishman, James Moore. His grandson, John, believes Moore is buried near the reservoir. In winter, the reservoir froze for skating; national and international ice-skating events were held. In February 1893, Jack Selby drove a coach and four horses across the reservoir. Towards the end of the 19th century, urbanisation led to the end of this hedonistic chapter. The Midland Railway built its Welsh Harp station in 1870 on its new line from Bedford to St.Pancras. The area lost its attraction with the development of West Hendon between 1895 and 1915 and the station closed in 1903. Naturists gathered at the Welsh Harp from 1921, until in June 1930 about 250 sunbathers were attacked by 200 objectors. This is referred to as "The Sun-Bathing Riots". Later the reservoir was popular for speed boat and other water sports, until its size became unsuitable. In December 1963, the reservoir froze over completely and it was possible to walk across the lake from the Neasden side to the Kingsbury end.

War history
The Mechanical Warfare Department, part of the War Office based nearby in Cricklewood, used the Welsh Harp for secret tests of a new weapon from 1916 - the Tank, especially the amphibious Mark IX tank. Early film of these tests was shown on British Television in the late 1990s. During the Second World War, a seaplane kept on the reservoir was rumoured to be an escape route for the Prime Minister. Local residents have recounted swimming to the plane.

Wildlife and nature conservation
During construction, the Welsh Harp attracted uncommon birds. James Edmund Harting and Walpole-Bond were regular visitors and shot many birds. Harting documented these in his 1866 book the Birds of Middlesex. They included rare vagrants to the UK such as Little Bittern, Squacco Heron and White-rumped Sandpiper. This started an interest in the birds of the Welsh Harp that continues until today, giving a unique historical perspective of a site in London. The next prominent ornithologist was William Glegg from the 1920s onwards and he wrote a paper for the London Naturalist in 1930 called 'The Birds of Middlesex since 1866, then a follow-up book to Harting's in 1935, called A History of the Birds of Middlesex. After the Second World War, a new generation of ornithologists took an interest, such as Professor Warmington, and Eric Simms (Naturalist), who lived just south of the reservoir in Dollis Hill. They were joined by Dr Leo Batten in the late 1950s. He still visits the reservoir today and was one of the movers in setting up the Welsh Harp Conservation Group (WHCG) in 1972 to fight off development. The WHCG has worked to protect the area as a nature reserve, including preventing a golf course and driving range from being built. The WHCG produces an annual report and also published a book about the reservoir ”“ Birds of Brent Reservoir ”“ in 2000, which includes chapters on the social history, the effects of urbanisation, the habitats, as well as a study of the birds and other wildlife. The WHCG organise management work, such as annual refurbishment of the tern rafts and work with Brent and Barnet councils on site management, including applying for National Lottery bids. The reservoir and much of its shoreline is a Site of Special Scientific Interest, mainly due to the diversity of breeding waterbirds. It is the only SSSI in Barnet and Brent. The reservoir and surrounding area is a Local Nature Reserve.

Birds of the reservoir
The reservoir is an important site for breeding waterbirds such as Great Crested Grebe, Gadwall, Shoveler, Common Pochard, Tufted Duck and Common Tern. At one stage, the reservoir was second only to Rutland Water for the most breeding pairs of Great Crested Grebe in the UK. Other breeding birds include eight species of warbler. In 2008, the first nesting attempt by Great Cormorant took place as well as the first nesting attempt by Grey Heron for several years, neither attempt was successful. The reservoir has always enjoyed a reputation for rare birds. As well those documented above during its early days, it attracted two Black-winged Stilts in 1918; the first Great White Egret in London in 1997; Blue-winged Teal in 1996; Lesser Scaup in 2003 and Penduline Tits in 1996 and 1997. Remarkably for an inland site, it also attracted rare warblers, notably Aquatic Warbler in 1955, Hume's Warbler in 2004, Yellow-browed Warblers in 1994 and 2003; however, most significant was an Iberian Chiffchaff on 3 June 1972, the first record in the UK. The current list of birds recorded at the reservoir is 250 species. The most recent species added to the list was Montague's Harrier in September 2009.

Many other forms of wildlife have also been studied and were documented in the WHCG book. There have been 28 species of butterfly at the reservoir, including breeding Marbled White and Ringlet, the closest site for these to the centre of London. Scarce species include a single Dark Green Fritillary in 1999. Prior to the construction of the reservoir, marsh fritillary used to breed. Dragonflies have been studied and 15 species have been seen, of which 12 breed at the reservoir.

Few mammals are seen, the grey squirrel the most obvious; the red fox is common but mostly nocturnal. Muntjac have been present since the beginning of the 21st century but are shy, their presence noted mainly by tracks although there have been a few sightings during the day in 2008. The reservoir is notable for bats with three species of pipistrelle, noctule, Leisler's bat, serotine and Daubenton's bat all recorded on a single day in September 2007. Regular bat detection evenings throughout 2008 have shown that Nathusius' pipistrelle is present and may be breeding at or near the reservoir.

Neasden Recreation Ground
Neasden Recreation Ground is a park of 4.5 hectares on the southern shore of the reservoir. It is mainly grassland with woods, a sports ground and a children's play area. There is access from Aboyne Road and from North Circular Road, opposite Brook Road and close to Staples Corner.