Interesting responses guys - thanks...

The blow by (warm engine cap off) is present but it doesn't seem too terrible to me - not as bad an Audi I once went to see - I could hardly put the cap back on!

Marvel does indeed sound like a marvel. I'm now guessing it is something like that as I think the car had been standing for a long time before I bought it. It needs a bit of love and a good clean in some places.