This article is about the current B251 in Bromley. For the original B251 in Erith, see B251 (Erith).
The B251 is a short road near Bromley in south London. The road was originally unclassified but had gained its number by 1932, making it an early example of a recycled number.
The route starts at a roundabout on the B230 and heads east along the suburban Hayes Lane, its name already indicating the B251's final destination. The road soon bends sharply right to head more southerly and then meets the B228 at traffic lights. As we descend into Hayes there's a short service road for houses on the left, after which a few bends see us heading eastwards once again.
We pass the unclassified D1 Station Approach, which is lined with shops, and then climb through a park before ending at a mini-roundabout on the B265.