It's the XC120 frame (I think the freeride is the same except for some extra gussets at the front?).
Went out on the Downs and into Stanmer woods to join up with the Brighton MTB ride last night.
Some bikes you just seem to 'click' with - I can't express how pleased I am with this - it just feels spot on.
I'm running a 140mm fork with a fair bit of sag so I suspect it's no taller than a lot of 120's - certainly the front end didn't wander on climbs (even locked out) or try and tuck in on slow stuff. I'm not that hard or heavy a rider so I'm not too worried about exceeding the nominal travel the frames designed for so I'll probably stick with it.
I've got a Decade versa I run singlespeed with the same model forks (at 120mm) and the Curtis feels similar (a very good thing - the Decade is a great frame) although the Curtis does have a bit more spring at the back but also more stiffness at the front, if that makes sense - it seemed to skip across wet roots.
Just really glad I took a gamble with not much research and with some doubts as to the published geometry, tbh.