Filling Gaslow Bottles

[Basildog]

It appears to be coming from around the filler neck its as though there is suddenly a blockage in the filler tube.

So you mean where the filler gun is connected to your bayonet fitting ?
It could be the seal on that particular pump or more unlikely you have a dodgy bayonet fitting.

 

[Larrynwin]

Having had LPG converted RVs in each case when releasing the bayonet gun there was always a brief release of gas which is trapped between tank and gun seals, from memory the LPG pumps had a label warning of this.