UPDATE TIME !

Problem no1: The tank would not hold pressure.
The rubber O ring in the filler cap hard gone very hard.
I sprayed it with WD40 and "worked" it with my fingers to try to
soften. It then held pressure.

I used paraffin on the wick. Worked OK, but probably so would have
meths.

Paid a totally outrageous 7.99 for 5ltr paraffin at our local rip-off
garden centre.

Problem no.2: In use.
The "Tap" must be leaking. Looked very liquidy up the long pipe to the
tap. (I'm pretty sure the fuel). As a result I tended to have flames
running up the pipe. It didn't make me feel very safe. (Hot, but not
"warm and cosy" if you see what I mean. I suspect a similar problem to
no.1, as pipe, tap and brazing look OK.
I'll check into it.

Problem no.3: In use.
Not really a nice, small pointed flame.
Due to insecurity feelings, I didn't mess too much at the time. I
don't really know whether amount of tap opening, or pressure, or
combination is supposed to control the flame.