The Austin London Taxicab used a modified Austin Heavy Twelve-Four chassis clothed with new bodies designed by London's largest taxicab retailer and dealer Mann & Overton, and made for them by London coachbuilders.

Mann & Overton Limited owned and operated a motor vehicle dealers business previously known as Mann & Overton's and established 14 May 1901 which came to specialise in the supply and financing of London taxicabs, first Unic then Austin Taxicabs, eventually holding the concession for the Austin taxicab chassis for the whole of the Metropolitan Police Area of London.