
I've removed the washers - the rusty looking bit plus one other inside but this 'bit' in the middle seems to be part of the bottle - it's an old Bass bottle which I just noticed says 'Retest 2000'...
I decided to look around again to see if I could get another one. AirProducts have said they'll give me a bottle but it's an "Argon/C02 mix" which I have no knowledge of - doesn't sound like pub gas to me though. BOC didn't want to know as soon as I said 'pub gas' as they only deal with the pubs themselves (!)