Amazon sell that one, so will get some. (I hate Amazon but sometimes it's useful - and it's a worthwhile challenge to find cheaper suppliers!) It gets only one poor review (plus one saying it's too expensive!) unlike some of the other products which moan about flaking, colour and everything. I'd prefer a brush on one, can apply just before leaving the boat and then come back after a few days and set a fire to cure it. I can't easily get the stove outside, I've just installed a new flue.
Thanks for all the comments.