Mews... wooden stable doors... We make think we could make a good guess as to what this building's purpose was. However, it never housed horses but is one of London's oldest car parks, in Wells Mews near Oxford Street.
London probably had the world's first multi-storey car park, at Denman Street, which opened in 1901 and closed as recently as 2008. Its owners, City & Suburban Electric Carriage Company, had quickly added several more sites in Wardour Street and Westminster. The latter was known as 'Niagara', in tribute to the company's most popular model of car.
These inner-city multi-storey car parks didn't have the ramps between floors which we expect today. Instead, they had electric lifts - and the one in Wells Mews is still in use today. Marks on the floor suggest that there may have been a turntable, too.
The car park remains in operation, run by NCP and serving the Sanderson Hotel. (This occupies the wallpaper company's former premises, designed by Reginald Uren, and is rather typical of its own, later decade.)