it's not a long squeeze as I remember, but small enough to have to take your helmet off. I had a look for it yesterday - was all equipped with a folding ***** so I could widen it if necessary but couldn't find it! I'm usually pretty good at finding stuff like that, but for some reason, even though I've tried to visit it half a dozen times, I've only found it twice, and I wasn't equipped for it, or couldn't risk getting muddied up at the time.
I'll probably be going back over the weekend for another try!