After Savoy Circus the road, dual carriageway, takes a bend towards North Acton, crossing the Great Western Main Line as it does so.
In the final few miles of the road, there are minor junctions with the A437 (Hillingdon Circus) to Ruislip and Hillingdon, and with the B467 (Swakeleys Roundabout) to Uxbridge, before the road ends at the junction with the M40 at the Denham Roundabout, northwest of Uxbridge.