Sounds like you have been talking to Licencing who do not appear to know their own rules, it's ok sticking none aviation people in there, but i always find they appear to not know what is what..
According to the 2007 ELGD on their website
A11.2
Category B1
A category B1 certifying staff authorisation permits the
holder to issue certificates of release to service
following maintenance, including aircraft structure,
power plants and mechanical and electrical systems.
Authorisation to replace avionic line replaceable units
requiring simple tests to prove their serviceability is also
permitted.
Note: Compass compensation and adjustment
certification privileges are contained within a
Category B1 AML.
A11.3
Category B2
A category B2 certifying staff authorisation permits the
holder to issue certificates of release to service
following maintenance on avionic and electrical
systems. Category B2 certifying staff can qualify for any
A sub category subject to compliance with the
appropriate A sub category requirements.
Note: Compass compensation and adjustment
certification privileges are contained within a
Category B2 AML.
A11.4
Category C
A category C certifying staff authorisation permits the
holder to issue certificates of release to service
following base maintenance. The authorisation is valid
for the aircraft, in its entirety, including all systems
That's on page 15 of the actual document, see
http://www.caa.co.uk/docs/177/8355%20Section%20A_07.pdf
I cannot see why it can possibly have changed.