Loft insulation heavy hessian blanket?

[Secret_Sipper]

I'm in the process of boarding out the loft and I've been up and filled in all the gaps in the insulation with new stuff and topped up where its been squashed down.

My question is, has any one ever seen what I can only describe as a heavy hessian type blanket over the rafters? It only seems to be around the bathroom area and wondered if it was there for any reason or if it should really be removed? I've cut around where I've needed to fit the loft legs but I didnt want to disturb it any further without knowing what its there for. Unfortunately I don't have any photos but come tomorrow night/weekend I will probably be back up there finishing off.

House is approx 1970's

We are have a few mouldy spots on the ceiling primarily under that blanketed areas wondered if this was hindering and trapping moisture rather than allowing the moisture to be taken away with natural air flow on the newer fibreglass alternative.

I'd rather take it out now while I still have some of the floor up rather than needing to dismantle it again. I have allowed for access points by citing the tounges off the boards but it covers quite a large area.

Thanks