"Yes mate that tank looks sick! Hmm should probs do something bout those welds they look a bit shit well they look raw no they look a bit shit. Scared of grinding through them and doing more damage than good oh man up you giant fanny. Grinding disc makes my ears ring. What? Ha ha Dad loves that one. Wow this flap disc is magic. Shiny metal is niiice little bit here bit more there and some round under there. Oh fuck gone too far oh fuck gone too far everywhere. Cracked there as well. And there. Better at welding ow hot oops blown a hole no worries just fill 'er up. Easy now flap disc me old bugger and and smooth manouevre just weld that bit up and see how she looks. What the that used to fit oh fuck that's bent oh fuck whole bloody thing has warped."
This was my thought train whilst fixing the tank. I've summarised, it was like this all day.
The wassell tank had four holes at the back on the bottom for mounting and attaching pepcock. One had a brass screw in which I measured at 3/8" and 28 t.p.i thread. This, as far as I can tell, is a unique thread not corresponding to anything. Powerless to my 25/64" drill though.