According to this article 1 in 6 of the older gas meters are inaccurate
http://uk.finance.yahoo.com/news/You-being-overcharged-gas-yahoofinanceuk-2918963641.html

_________________
Mike
http://rebuildingatimberbungalow.blogspot.com/
any advice welcome

Our meter was changed a few months back, but our old meter was relatively new.

When I asked why it was being changed he said there were faults with the meters and some of them are still counting used gas after they have been disconnected

2 choices here test all meters taken out and assume the same inaccuracy from installation and add a further 10%off the reading or 1 whole percent if its sub 1 percent

or test a sample off 100 random meters discount any meters wildly outside the average and add 1 percent to the highest reading then then the wildly over reading meters should be traced back to owners and investigated further

_________________
we are all ------------------still learning