Having taken off the corner post in the front of the cabin there was evidence of why the leak was caused by
The sealant which was used when the yacht was build back in the 1930's was red lead sealant.
Which over the years as broken down and dried out and as caused the corner to leak through the joint between the cabin front and cabin side
As the area is damp and is in need of some drying out this is going to be left to dry out before resealng the joont and putting the corner post on a fresh bed of modern sealant which will move with the cabin side and cabin front
The corner post being left off to dry out over the weekend.