Garden shed - ventilation for foil based cold roof

[BCS1980UK]

I built a log cabin with a pitched roof using T&G as the roof bed. I put insulation boards with a ply skin on one side on top of the T&G and then put Wickes felt shingles on top. It has worked ok for the last ten years despite the high winds we often get.

Good to know, @HappyHacker
I am building this weekend my new log cabin with exactly the same solution.