Live in a 1930s semi, as far as I'm aware no work has ever been done on the roof.
There's an ever increasing amount of mortar in the loft space that is coming from between the slates on the roof. Obviously no felt in place.
Is this an issue that needs addressing? The house felt cold last winter and I'm beginning to think this a cause of that issue.
I'll be adding another post regarding insulation in the relevant forum.