simond said:
An individual is not allowed to adapt, change or extend the supply side pipework to a meter owned by the gas transporter without their permission.
But that's not the same as it being
illegal. Transco may have grounds for some sort of civil claim against you if you moved their meter without their permission, but surely no
criminal offence would have been committed.
On the other hand, it is definitely
illegal for Transco operatives, who are not Corgi Reg. in their own right, to carry out gas work on a self-employed basis. Anyone asking them to do so, knowing full well that this was illegal, might arguably also be guilty of a criminal offence.