Frontiersmen stand to be scrutinised by Major-General Francis Lloyd at Horse Guards Parade, Whitehall. Charged with the defence of London during WWI - no mean feat! - Lloyd earned the nickname 'The man who ran London'. In the film's second section, the troops marching through the West End would have been looking forward to a rare night of cinema entertainment before being despatched to the Front.
Founded in 1905, the League of Frontiersmen was a paramilitary group originally formed to protect Britain and its empire from the threat of invasion; the organisation never fully recovered from the casualties inflicted by WWI. It is likely that the men in this film were the 25th Service Battalion, formed in February 1915 by Lieutenant-Colonel Daniel Patrick Driscoll. Many were Boer War veterans and older than the average soldier. The battalion served in Africa, largely in the area around Lake Tanganyika, British East African and German East African territory.