One or two Gran.
Any latch would do really .. not like anyone can break in a nick the gas at night! : ) anyways .. See below.
This is advice found for Wales and West Utilities. So ring your team and see if they can fix your box lol.
Under the Gas Act 1996, the domestic meter box is part of the fabric of the property and as such is the responsibility of the property owner/occupier to ensure it is adequately maintained. All repair/replacement work is chargeable.
Please contact the meter box team directly on 02920 278637 for an application pack. The pack contains an information letter, price list and a meter box description leaflet.
There is no charge for Hinge Pins/Locks/or keys.