Local ratebooks date what became Allen Street (also ‘Allen’s Rents’) to 1817.

Thomas Allen was a ’Buckinghamshire gentleman’ and landowner. He was one of the innovators of stucco, according to Faulkner’s History of Kensington (1820): "Mr Allen is now building two large rows of houses in the modern style, covered with plaister to ressemble stone". Faulkner denounced this as "tasteless tasteless innovation".

Allen formed a street leading south out of Kensington High Street of ’similar width and character to Newland Street’. This cul-de-sac was the future Allen Street but was then called Phillimore Terrace.

While active all around, in Allen Street itself, Thomas Allen did not build and until building started on the estate to the south, Allen Street was a quiet side street. The southward extension of the street occurred from 1852.

The Britannia Brewery occupied the site of the present Allen Mansions since 1834. After an expansion, the figure of Britannia looked up Allen Street. Under various owners, the brewery survived until 1924.

Shaftesbury Villas continued the line of Allen Street south between the brewery and Scarsdale Villas. South of there, this part of Allen Street was originally Inkermann Terrace named in the 1850s after the Crimean War. There was an Alma Terrace here too, named after the same war.