LONGBOW was an early 20th century counterpart of the Unified Intelligence Taskforce which operated circa World War II. (PROSE: Just War, Christmas on a Rational Planet, et al.) This world security organisation was set up by the UN precursor, the League of Nations. LONGBOW dealt with the occasional extraterrestrial incident, but was disbanded after it, and the League, failed to prevent World War II. (PROSE: Just War)
History
Kadiatu Lethbridge-Stewart covered LONGBOW in The Zen Military - A History of UNIT, suggesting that it had its roots in earlier 18th century secret intelligence groups such as the Shadow Directory. (PROSE: Christmas on a Rational Planet)
In 1939, LONGBOW's Operation George saw them fighting a dragon. (PROSE: Moon Blink)
Circa the early 1940s, LONGBOW built Dolerite Base underneath Edinburgh Castle to use as a secret base. (PROSE: Moon Blink)
In 1940, the Sixth Doctor, Emily Chaudhry, and Will Hoffman visited Edward Grainger in London and rescued a Mim which had been stranded on Earth. Grainger filed a report on this incident that was originally kept in LONGBOW archives (PROSE: Incongruous Details) in Whitehall. (PROSE: Defining Patterns) The Doctor and friends attempted to find Grainger's report in UNIT archives in the 2000s, but discovered that they had been destroyed in 1957. (PROSE: Incongruous Details, Defining Patterns)
When giving his companions fake identities for living in 1941, the Seventh Doctor made Roz Forrester a military officer with LONGBOW clearance. (PROSE: Just War) At a later point, Roz remembered LONGBOW as an organisation that was familiar with the Doctor. (PROSE: Christmas on a Rational Planet)
In 1969, after the London Event, Oliver Hamilton secured Dolerite Base, which had been out of use since LONGBOW's disbandment, for the Home-Army Fifth Operational Corps to use as a base. (PROSE: Mutually Assured Domination) The base was refurbished a few months later, (PROSE: Moon Blink, The Grandfather Infestation) and Alistair Gordon Lethbridge-Stewart gained access to some of the old LONGBOW files in storage there, including a report from Winston Churchill that mentioned Project Ironside. (PROSE: Moon Blink)
In 2000 Patricia Haggard arranged the transfer of old LONGBOW files from Edinburgh. (PROSE: The Last Dose)
On 1 June 2019 Giles searched through the LONGBOW files details about Varunastra. (WC: Varunastra)
Behind the scenes
When asked on rec.arts.drwho what LONGBOW stood for, Just War author Lance Parkin admitted he only came up with "League of Nations Global..." He accepted Chris Schumacher's guess of "League Of Nations Global Bizarre Occurences [sic] Watch" as the "right answer". [1]