Thanks for the info!
However after a huge amount of searching on Google, I haven't managed to find anything like it. There are elements of
the PTF/Nasty, the PCF Swift boat, modern US PBs, and post-war Vosper patrol boats in the design, but it doesn't match any of them exactly.
I can only assume that it's a fictional "freelance" design based very loosely on real patrol boat designs.
Anyway, I'm going to use the hull (motorised) as the basis for a scratchbuilt model, possibly a PCF Swift boat. (I know Revell make a 1/48 kit for this boat, but I haven't managed to find it anywhere here in the UK, even on eBay, and I enjoy scratchbuilding, anyway)
Just about everything from the deck upwards will have to be made from scratch, though!
I bought this for £2.99 from a market stall, I thought it looked like a real design rather than a fictional toy, and at the very least I'd be able to use the hull for a scratchbuilt model.
Obviously I was wrong on the first point though! I'll post some more photos when I get round to building a new deck and upper hull.