I have had this problem for many years. In 2007, about a year after I purchased the house, the roof was replaced (insurance claim) following storm damage. The problem only occurs in very heavy rain from the south. The flashing between roof and the house wall has been replaced several times but does not cure the problem. Internal damage to the house wall is now appearing. The suggested remedy is to replace the conservatory roof, but I can't see how that would cure the problem.
What's causing the water ingress and what's the solution?
Here are some pics.
What's causing the water ingress and what's the solution?
Here are some pics.