The Fellowship of Reconciliation, London Union was established in 1916 when FOR branches already active in London met and decided that a London Union council of representatives would best represent them. The existing branches continued to meet with branch representatives attending London Union meetings and influencing London Union policy. As the largest group of the Fellowship of Reconciliation the London Union had its own office and staff who represented London members of the Fellowship of Reconciliation, and organised campaigns, conferences and events. The London Union Secretary worked closely with the British Fellowship staff and committee, keeping up to date on policies and campaigns but at the same time enjoying far greater autonomy than other groups. Working as London Union Secretary inspired devotion from staff as only two held the post from 1925 to 1983, Beatrice Brown from 1925 to 1943 and Leslie Tarlton from 1943 until his death forty years later.
The London Union were instrumental in providing much of the Fellowship's social work activities. They established the Children's Hospitality Committee in 1919, initially organising holidays in Britain for starving children from Austria. The committee ran until the mid-1950s organising holidays for children from London slums in the inter war period and beyond and from Germany after the Second World War. From the late 1920s to the early 1930s a Welsh Girls Committee operated which found work for girls from the deprived south Wales coal fields as domestic servants in London. During the Second World War the London Union helped run the Hungerford Club in Westminster which acted as an air raid shelter for London's homeless population who were refused entry to many public air raid shelters as they were deemed a menace to public health.
The London Union promoted the rights of conscientious objectors, campaigned against the war in Vietnam and sought an end to the troubles in Northern Ireland. The London Union was very socially active with an annual new year party, a summer garden party and a rambling group. Lectures and talks were regularly held featuring celebrated pacifists such as Vera Brittain. International FOR members were welcomed warmly to London in the period surrounding the Second World War with the London Union committee organising events especially for them.
In the decades following the Second World War the London Union suffered a continuing fall in membership numbers, this was a common problem across the Fellowship of Reconciliation nationally. With fewer members there was less money to run the Fellowship of Reconciliation and the London Union came under increasing pressure from the British Fellowship to make cuts and reduce costs. Leslie Tarlton battled to maintain the London Union's resources arguing that the London Union had more members than anywhere else in the country. During the mid 1980s the London Union became fully integrated with the nationwide Fellowship of Reconciliation and its name was changed to FOR London.
Information on the formation of the Fellowship of Reconciliation (England) can be found in its archive, COLL MISC 0456.