In theory yes, but very fool hardy, unfortunately purpose built Gas bottles whether it is underslung or calor style bottles have a built in safe guard so that the bottle can only be filled to 80% capacity, the reason being that if over filled beyound the recommended 80% gas in liquid form can arrive at the hob/oven/heater or fridge and that is not a situation that you want to happen. 7.5 and 15ltr bottles as rented from a gas supplier such as calor gas or Flogas fill their bottles by weight on scales so that the need for a shut off valve at 80% is not required. What you are doing with this method from ebay is a matter of luck that you do not over fill the bottle unless of course you have the bottles on very accurate electronic scales and know what the filled weight of the bottle make should be, there are some details of bottle empty weight and bottle full weight on the web, but in honesty I would advise you to find second hand gaslow bottles which do have the 80% valve or an under slung tank made for purpose.


Phil
P.p.s Autogas 2000 to my knowedge there is only one company based in Birmingham
Here is the link.
http://www.autogasleisure.co.uk/