The Metering & Billing Approval Bodies' Forum comprises the two UKAS-accredited organisations:
British Approvals Board for Telecommunications (BABT)
British Standards Institution (BSi)
Ofcom oversee the Metering and Billing Accuracy Scheme and further details will be found on their web site:
The 2008 Ofcom Metering and Billing Direction is available here:
Other links:
Ofcom list of Approval holders
Ofcom list of Approval seekers
Further information is available from the "Public Information" link, which also appears in the left-hand margin.