Thanks for the replies. There's no condensation in the loft, but then again there are some pretty loose sections in the membrane where I can see the tiles above, so maybe there's some ventilation happening there.
I pulled back some of the insulation at the edges and there isn't any damp or mould...
My first post on the forums after lurking for a while.
I've just moved into a new house and peeked my head in the loft to find the insulation setup is different to what I've seen before. As well as just 100mm between the joists (that I'll be adding more to soon), there's a line of insulation at...