Anyone recognise this 70's dual carriageway in London area

oiltreader:
Hello Gene Hunt, fellow flickrite, the AA sign looks a tad too close to the carriageway and therefore could be a film prop on any route out of London, just my offering.
Oily

Hi Oily - Yes, it’s my thought too that the sign was a prop. I’m convinced that they would not have ventured too far from Harrow Road / North Kensington to film this scene though as it amounts to about 5-10 seconds total.

DEANB:
Hello Gene, Out of intrest what film is that ■■?

Hi DeanB. The film is Steptoe & Son Ride Again. It was filmed in early 1972. I have managed to identify every location on the film except this one. I’m still looking into the suggestions offered above. The Great Cambridge Road A10 (as suggested by Wheel Nut 3) is a long road so it’s taking a while to look through that on Google Maps. The A414 near Hatfield (suggested by Pete Smith) also looks a good possibility.

Thanks to all of you for your thoughts so far!