Denham Roundabout

It was originally opened in 1943 in conjunction with the completion of the new Western Avenue route into west London.

The Western Avenue took over the classification of the A40, with the previous route to London, via Uxbridge and Ealing, being reclassified as the A4020.

The roundabout also included a new link to A412 that formed part of the outer London orbital route.

The roundabout below facilitates junction 1 (J1) of the motorway to connect with the westbound continuation of the A40, together with the intersection of the road from Uxbridge (A4020) and the road from Slough to Watford (A412).

[1] When the M40 from Denham to High Wycombe was built, Western Avenue was extended at high level to make an end-on join with the motorway, and a larger roundabout was built below the bridges carrying the motorway.