Thanks for all for the advice.

Went to the physio today and her view is that one of the discs has split a bit. The gunk which has leaked out is affecting the sciatic nerve hence the pain and p&n. The recommended stretch is lying on my front then pushing up with my arms and holding that position.

Reckon I'll rest it for a couple of weeks but do some light walking on the fells. Not sure if swimmig might help. Also need to stop seeing it as an excuse to drink wine as not running.

Worse thing was walking to the shop tonight and bumping in to the club off to do hill reps!