Thanks for the advice but the only electric in the system is where the on a valve after the petrol pump which I assume cuts off the petrol supply when the LPG is switched on (the LPG is joined with a y connector onto the fuel pipe just after if I rember right, it is a very old system and very basic
There would still be a solenoid on the tank to operate the valve on there, and should be another up the front as well near the input to the vaporiser though maybe that one isn't present. Otherwise all the gas in the tank would not be able to be contained when required.
Some photos would help with the diagnosis - if you can get some taken theres a sticky post at the top of the forum showing how to link to them, if your struggling with that bit once you've got the photos taken then drop me a pm or post back here and will work out a way of sharing them with those who can help you.
Otherwise you will be looking for an installer to assist - as said pretty sure Blaze have shut up shop given Rossko hasn't been on here in over a year now, and their website has gone. A single point system could prove a challenge to some installers to fix, so you may have to travel a bit to find someone to look at it.