So is this the only vent? I was hoping for a blocked vent to be causing the crank case/rocker box pressure, but if this is it then its more serious like rings I guess?

And Kerry, I'll look for a vacum pipe once it stops raining

Can someone please tell me there is another vent?

I must get a book on the engine.

It's done well so far as it came from North of Stockholm and has driven to South West England with two horses.

Thanks, seems like a good forum.