It started on the A407 on Willesden High Road and headed northwest. In 1922 Willesden was on the edge of the urban area and so the B452 headed into open country. It went through the village of Neasden before ending on the B454. Neither road continued beyond this junction.
The B452 did not last long. In the mid-1920s it was upgraded to Class I status, becoming the A4088. This road continued beyond the junction with the B454 and on into Wembley. The B452 number was quickly reused further west.