It's possible they may have made the tanks for Harris - they made the original tanks for Seeley and made me a big tank for the IoM.  However they needed my bike there to fit it so if they aren't the original manufacturer they wouldn't have a pattern so you could be a bit stuck!

 

Pearsons have no website or email so you'll just have to phone them.  In fact I think electricity is a recent addition to their workshop - it's a bit "traditional"!

 

Failing that all I can suggest is try and get in touch with Steve or Lester Harris to see if they can remember who made the tanks - as you say they aren't very communicative if they don't think you're a customer with money to spend.

 

Good luck!

Des