Prescelli mountains? Lovely. You picked a nice week for it
I certainly did. Couldn't believe my luck. I travelled east to west from Crymych to Little Newcastle. The wind was behind me, which made ALL the difference. As I said in an earlier post I had the advantage of being dropped off at one end and picked up at the other with a bail out point at about halfway. Totally dead at the end (intermittent Orange signal) but it was a very good ride.
In wet conditions I reckon half way would have been the max for me simply because of the peat on top
I'm happy to scan in and send you the OS sheet if you pm me your email address.