In 1900 and 1901 the Napier Lambeth works was only producing cars on a relatively small scale. Car production increased from 1902 so it must have become apparent to Montague that the Victorian works in Lambeth that had served his grandfather, David, and father, James, so well were no longer going to be sufficient. At this time early motor car makers generally assembled parts bought in from motor factors but David Napier also took the decision to make the essential parts in his own works. The fringes of London had been developing rapidly throughout the Victorian period, with green fields giving way to industry, supported by a well-developed train network. One such area was Acton, in North West London, where David purchased an initial 3 ¾ acres in 1902 in Acton Vale, on the south side of the Uxbridge Road. Work began immediately on the construction of a stone-faced brick factory to meet the growing demand for Napier cars.
The new site had a newly constructed works and a grand office block designed by the architect Robert Thompson and include a fine foyer suitable for car display that was latter named ‘Piccadilly Circus’ by many of the staff. The new workshops were better arranged for production of the vehicles. The site also had facilities for internal combustion engine design, manufacture and testing. Whilst some of the most accurate machine tools were brought from the old Lambeth Works most of the tools were new.
By 1904 there were some 500 people employed at Acton, a number that was set to triple over the next few years, necessitating the purchase of further land for the continued development of the works. In 1916 a new concrete named the Eastman Building was constructed facing on to Acton Vale which still stands today albeit refaced in glass and used as an Access storage facility. As further Napier sites were developed around the area this original site was named Acton 1. There was also Acton 2 built on the old Stewart & Arden offices and the Coronation Road Test Tunnels at Park Royal.