It looks like an updated version of the Trigon fork that I've got on one of my bikes.
I'm using 28-622 tyres and there's loads of room for bigger.
I reckon that 42mm tyres would fit.
Why not get in touch with Trigon's UK distributor ? :-
http://www.trigon-cycles.co.uk/contact
FWIW, I got my fork off
Ebay for a fraction of Trigon UK's price. The fork was only available from Ebay when I bought it.
.