Thanks again Matt - we did that ridge fprm Pen yr Ole Wen to the upper Afon Berthen in descent a few years back, but veered across lower down to the waterworks on the Afon Llafar and thence down to Bethesda.
I collected water on the way down from Llewelyn, I never use a water filter or treatments of any kind.
TbS - thank you, that ridge is a fine ascent route and enables a traverse of Yr Elen, rather than the usual out-and-back from the Llewelyn side.
Boos2 - When I thought about many of our tent pitches in the past, I really wasn't happy with that ultra-thin HH1200 groundsheet. It would trust it on benign terrain but I want more confidence in kit to tackle rougher stuff, so I had it replaced with thicker HH5000. It increased the weight to 1.29kg but that's still a good figure.