They are/were a CAA approved Part 145 Over Haul Facility for numerous aircraft components and engines.
It is no difference to some Maintenance Organisations being approved by CAA/FAA/CASA/EASA to maintain/repair/overhaul Bell helicopters. That doesn't make them a Bell CSF, but they are still authorised and approved to do whatever their Airworthiness authority allows them to do.
They may not have been a factory approved facility, but they are a CAA approved facility.