Why do you leave your battens hanging out every where? Just must be more work once its tiled and if the verge has been bed with sand/cement on an undercloak?
get a price to overhaule your roof ie. fixing the slates pointing that needs sorting.but at 90 years old the roof prob got nail cancer so slates will keep slipping. if this the case why spay it with something when it needs a new roof :)
use a torch! :lol: Its clear as day the steps are well wrong they angle bout 45 degs off the roof these are more straight up if not going back the way. the box gutter is not slated correct and the split in lead sets it off well.