Colin, true, but there is a lot of water based stuff out there now..the last lot of red oxide I bought was water based and was not as thick as some I have used before.Come to think of it, I had trouble finding much other than water based paint (I was after some matt black to do the front porch light with) in Wilkinsons.
A smallish tin is not too expensive and it can be used on ships bottoms, rusty tools,lawnmowers gates cars etc etc.
Ashley