START: adjacent to lay-by on A476 by CARMEL village sign. Proceed north towards Llandeilo to TURN SHARP LEFT with great care (5.2 miles) onto B4300 (M). Proceed south on B4300, through Llanarthne (10.5 miles) to TURN LEFT onto B4310 (M) signposted NATIONAL BOTANIC GARDENS. Climb hill past Y POLYN restaurant, through CEFN ABBEY and descend to roundabout at NATIONAL BOTANIC GARDEN entrance (16 miles). Go straight on at r-a-b (2nd exit) with care (r-a-b is offset to left) to next r-a-b where go straight on (2nd exit) to pass underneath A48 flyover (16.7 miles) and into village of PORTHYRYD where TURN LEFT with care (17 miles) on unclassified road signposted CEFNEITHIN (M). Climb hill to village of CEFNEITHIN to FINISH by field entrance approx. 200 metres past Cefneithin village sign (19.5 miles)