A40 road in London

In London, the A40 forms a major trunk road starting in the City of London, and passing through six London Boroughs: Camden, Westminster, Kensington & Chelsea, Hammersmith & Fulham, Ealing and Hillingdon, to meet the M40 motorway junction 1 at Denham, Buckinghamshire. Outside London, the road then continues onwards to Fishguard, Wales.

The road has been re-routed several times in the last 100 years – part of the route of the London section of the A40 was laid out in the 1920s and 1930s when Western Avenue was built – now most of it is grade-separated, dual carriageway (divided highway). In the 1960s Westway was constructed, easing traffic access to and from the centre of the city. The A40 links the City of London and the West End to the M40 motorway and M25 motorway. The route is called The London to Fishguard Trunk Road (A40) in legal documents and acts.