Outline : This is a pleasant walk with a strenuous middle part. The start is through farm yard and fields to join the main EW for a fairly stiff but very pretty descent and ascent. Coming off the EW through fields it then joins a farm track and then a short uphill on road back to the start.
Map : All grid references are from OS Explorer Maps 181 or 188 – Builth Wells
Start and Finish Point : Point 1, 984375
Walking Time :- about 2-2.5 hours
Ascent/descent: - about 150m down and up, fairly steep
Access/Parking : Access to Point 1, 984375 Merthyr Cynog is off the B4520 or from Brecon via Cradoc and Pont-faen. Some parking.
From Point 1 (SN 984375), take the NW corner of the square at Merthyr Cynog through a farm gate, climb the well defined bridleway track NW for 1.3 km to cross the SENTA boundary at Point 2 (SN 976384), passing a defunct sentry post (vedette) and the red flag. The gate here does not open and has to be climbed over. You then reach the Epynt Way at Point 3 (SN 975386), marker post 806. Follow the Epynt Way marker posts until post 833. Also see pages 31-2 of the Official Guide Book. This part is a delightful walk albeit quite strenuous. Turn right at the junction, pass West behind a plantation, then follow the boundary fence gently downhill. As you reach the corner of the fence line at Point 4 (SN 978391), the busy military road known as "Route 61" will come into view far below. This road marks the boundary of the live firing area. It must never be crossed. Continue downhill, leaving the fence to follow a stream down to another internal fence corner at Point 5 ( SN 979392). Turn right here to head down across fields, crossing a small stream through a hedge line to reach a 12' gate beside the Yscir Fawr River at Point 6 ( SN 982391).
This is where the path briefly leaves MOD land to avoid a live firing range. Make your way along the hedge line to reach a tarmac roadway and then turn left to cross the river via Tir Bach Bridge. Continue along the roadway for approx 150m then move up the field and go through a bridle gate in the hedge line. Re-enter the training area behind the range warden's premises, via a further bridle gate across another stream - point 7 (SN 982395). Once inside the boundary, follow the hedge line up through two more bridle gates to ford the stream again. Follow the boundary fence all the way up to a gate at point 8 (SN 987398), leaving the Epynt Way route where it turns N, marker post 833. This descent and ascent is about 150m.
Exit the training area here through a gate, following a broad track (probably an ancient drover’s road) South to descend past Bwlchyddyallt farm point 9 (SN 990388). A farm road then leads to the Upper Chapel to Merthyr Cynog road above Pont Yscir Fawr at point 10 (SN 992382). Turn right here and follow the road 1Km SW to return to your starting point.
This circular route can of course be walked in the opposite direction.
Addendum (Map OS 188)
Circular walk 4, Merthyr Cynog can be extended or varied or this route followed as CR4b. These routes involve more of the EW, sections 7&8 as well as the boggy high moorland crest between Llanfihangel Nant Bran (Nant Bran river valley) and the Ysgir Fechan river valley by the Pont-faen/Pont Ryd-y-berry/Merthyr Cynog road. This route should be undertaken in good visibility.
Circular Route 4b. 2.5 hours.
This is reached by the road from Brecon to Cradoc, Pont-faen and Pont Ryd-y-berry with signs to Merthyr Cynog but not turning right to there but going straight on at Pont Ryd-y-berry to cross a cattle grid, past a red flag onto the training area. There is parking here or a little further on in the Llwyn-y-celyn receptor area, SN967382. Head west. Entry is by a horse gate down a muddy slope across a footbridge and then up though a small wood into fields. This ascent is fairly steep. Follow marker posts, 755 to 763, a bridleway marker post by a gate, 950379. The path bends to avoid a boggy area but otherwise follows the boundary fence. The path from the gate is not marked. Head south. It is shown on the map but is erratic. The initial objective is to pass between the trig point height 424, 957364, and small lake Lyn Dwr. Be careful not to go to the left as the hillside drops away very steeply. To go too far to the right brings you steeply down eventually to Llanfihangel Nant Bran. The going is moorland with clumps of coarse grass/reeds. There are multiple small streams and one boggy area of 60m or so. From the lake/trig point it is clearer and a fence line comes in on the left. The going is now soft. There is a change from moorland to grazing grass. There are very often larks here and it is possible to listen to them for up to half an hour whilst walking. The path drops down and then to the left. At points 965358 or 967355 join a path, going left and heading to Pont Ryd-y-berry and the road and river. Pass Cerrigeithon 977364 on your right. The path becomes a farm track and then joins a road to cross the river and reach Pont Ryd-y-berry. Then turn left to return to the start.
The route can be done in reverse.
This circular route 4b could be combined in several ways with CR 4 making circuits of varying length. This is best appreciated looking at the EW main map or OS sheet 188.
The longest would mean going up or down the hill to Merthyr Cynog (dull and hard) but would cover EW posts 833-763 so good going up and down and the above described moorland walk.