Getting "B"s UK weather proofed is a real pain.
Ours is out 24 x 7 x 365 with no protection or covers.
I have done some detailed mods to stop water ingress going below and into the the lower rear floor plan area BUT to be honest they are not perfect, should never be required and actually a basic design fault.
I say a design fault but that would be a little unfair. The "B" design, styling, etc is IMHO 100% just about the bees knees of sleek styling etc.
The hood repository with sleek covers/bodywork is top notch.
The water ingress problem is another complicated problem that I have been chasing for many years now.
I can provide more details from an engineering point of view but WE COME BACK TO THE OLD PERPETUAL PROBLEM OF SOFT TOPS.
They never have been, never will be, water sealed environments.
There are many makes of soft tops, folding soft tops / folding rigid tops, sky roofs, and even more traditional sun roofs that just LEAK. If not when purchased the x years down the line when the solution costs more than your vehicle is worth.
This summer, come long dry periods of weather, I will be working on our "B"'s water integrity yet again.