As the meter always remains the property of your gas supplier, so check through the following site
http://www.ofgem.gov....amm.aspx#who_can_move
Extract from the above:
You should initially contact your energy supplier or the gas transporter for your area in order to arrange for your gas meter to be moved. The gas transporter will normally carry out the meter move rather than the supplier, which means you can approach the transporter direct as an alternative to contacting your supplier. However, in certain circumstances a Gas Safe Registered installer may be able to carry out a meter move - further information is provided below. If you require contact information for your supplier or local gas transporter or further advice on moving your gas meter, please contact the Citizens Advice consumer service on 08454 04 05 06.
Also,
However, since the meter installation is most likely to be the property and responsibility of the Meter Asset Manager (MAM) - in most cases this will be your energy supplier - it would be necessary for the OAMI or Gas Safe Registered installer to first contact the MAM, seek agreement for the works to be undertaken, convince the MAM that the work will be properly designed and installed, safe and that the overall long term integrity of their meter installation is not compromised, and finally agree contract terms.