The B3407 follows part of the pre-bypass route of the A30 in Egham town centre.
Starting from a roundabout at the point where the A30 Egham Hill meets the western end of the town's bypass, it follows Egham High Street eastward into the town centre, ending in less than a mile at a mini-roundabout junction with the B388 just past the fire station (on the right). Not all of this short route still follows the High Street, however – the middle third having been diverted to run one block further south along the parallel Church Road, to avoid a now pedestrianized area.
The road number is unsigned at both ends and some maps show the route as a branch of the B388. Nevertheless. Surrey County Council's 2015 road lists confirm that, at the date of publication, B3407 was the correct route number for this itinerary.