"cynic" wrote in message

Ye canna change the laws of physics captain ...

That (and the other poster) is the best answer I have had so far. BG may
have official published specs agreed with CORGI but it is clear that I am
seeing problems with their distribution. On the cold day with big demand my
governor had not actually cut in to do its job and all I was seeing was
direct pressure fluctuations in my newly plastic lined old iron pipe. They
re-laid the gas big street main using a push in plastic liner which is
obviously smaller than the original iron pipe. I should have called BG out
on a cold day to get a more realistic reading. The evidence was lost on a
warm day and everything appeared to me normal, although I suspect I should
not see a 5mb drop at the meter if the actual street supply is up to spec.

Thanks for that explanation