Well, had another look this afternoon. There was a fresh drip on the hoses but the valve still looks fine to me. I'm more and more convinced that its a hose/connection issue rather than the valve itself. I did try to get to the clips to try and seat the hoses better but with the pedals in the way and some of the clips facing the bulkhead I just can't get any purchase on them.

The good news is all the fluids in the engine bay are good. Coolant still at max, and I did 30odd miles in it yesterday. I have in the meantime put some pieces of sponge around the hoses to absorb the weeping and will keep a regular eye on it. Will look to get it booked into Austins at some point to get it looked at, order another DMGRS valve as a backup and may as well get the plenum valve fitted then too seeing as I have one ready to go.