MkII engine cut out, won't start

Hullo, new to this forum but I've searched for this problem in the topics and haven't found a similar one. I have a 1989 1.6L CL Golf.
I took it out this morning, was driving it normally when the engine died, with no warning, spluttering or odd noises.
It will not restart, hot or cold. There is fuel in the tank, and it is reaching the carby. The plugs are sparking strongly. It seems to have normal compression, but I haven't put a compression gauge on it.
Anyone any ideas? Because this doesn't make sense to me, I've never known something to not start whe it has fuel, spark and compression.
Oh yes and it has been having the same problem with its auto choke as with sadjocko's post.
Thanks

OK, so I've done a compression test and the 3rd cylinder is way out. I suspect the timing belt which I'm about to confirm.
But is there any way I can check for serious internal damage without removing the head?
I've looked in with a torch and can't see anything, never heard anything either...