We've since found, and bought, one from Lidl/Aldi. Slightly cheaper, but slightly larger.... and fits absolutely perfectly in the campingaz stove.
These are both the non-stick aluminium type, which are good enough for us, but you can pay a bit more and get the cast iron ones.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.