The George pub, Church Lane
The B424 appears on the DfT road lists as Wembley - Church lane - Tudor Gardens, making it a road between the A4088 and A4006 in Kingsbury, north London.
However, this road is actually numbered B454. Although the number is a duplicate (with the other B454 in west London) the Kingsbury incarnation is the original one. It is possible that this was renumbered B424 at one time to remove the duplicate but if this was done the change has been reversed; the other options is it is merely a misprint.