The reservoir takes its informal name from a public house called The Welsh Harp, which stood nearby until the early 1970s.

Residential areas around the reservoir include: Neasden, Kingsbury Green, West Hendon and Cricklewood.

Regular traffic meant lock openings draining the local canals (several feet above sea level) leading to canal-water shortages.

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).

In 1891 Capazza attempted to launch his Patent Parachute Balloon – it failed to take off and accounts record 'nasty incidents' among the 5,000 spectators.

[citation needed] The reservoir was popular for speed boat and other water sports, until its size became unsuitable.

It also hosted the 1960 European Rowing Championships, which that year was for women only as the men competed at the 1960 Summer Olympics instead.

[10] The Phoenix Club provides: Canoeing, Kayaking, Bell Boating, Raft Building, SUP (Stand-up Paddleboard), Sailing and powerboat to members.

[13] In past winters the reservoir froze for skating; national and international ice-skating events were held.

During the Second World War, a seaplane kept on the reservoir was rumoured to be an escape route for the prime minister.

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.

After the Second World War, a new generation of ornithologists took an interest, such as Professor Warmington, and Eric Simms, who lived just south of the reservoir in Dollis Hill.

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 also organises management work, which included an annual refurbishment of the tern rafts until the silting up of this part of the reservoir prevented a safe approach to the rafts, and the group works with Brent and Barnet councils on the management of the site, including applying for National Lottery funding.

The reservoir and much of its shoreline is a Site of Special Scientific Interest,[17][18] mainly due to the diversity of breeding waterbirds.

At one stage, the reservoir was second only to Rutland Water for the most breeding pairs of great crested grebe in the UK.

As well as those documented above, it attracted two black-winged stilts in 1918; the first great white egret in London in 1997; the blue-winged teal in 1996; the lesser scaup in 2003; and penduline tits in 1996 and 1997.

[citation needed] The current list of birds recorded at the reservoir numbers 253 species.

[23] The most recent species added to the list are Caspian gull (2015), Ring-necked duck (2017) and cattle egret (2018).

[24] There have been 31 species of butterfly at the reservoir, including breeding marbled white and ringlet, the closest site for these to the centre of London.

Muntjac have been present since the beginning of the 21st century but are shy, their presence noted mainly by tracks, one or two are occasionally seen in daytime.

Neasden Recreation Ground is a park of 4.5 hectares (11 acres) on the southern shore of the reservoir.

Welsh Harp Open Space is a park and nature reserve of 9.43 hectares (23.3 acres)[26] on the north-west shore.