The B4586 is a link road in south Pembrokeshire. It was originally unclassified but gained its number in 1935.
The route starts at traffic lights on the A477 in Broadmoor. Although looking at a map may suggest otherwise, that road is on its original line at this point. Our road heads northwest through the village and reaches open country before skirting the edge of Jeffreystone, as it always has done. The B4586 descends into a valley and crosses three streams in quick succession before continuing north to skirt Loveston. We continue to climb and it's not long before the end of the road is reached, at a T-junction on the A4075.
An OpenStreetMap trace for this route awaits uploading to the SABRE Wiki.