On Thu, 22 Oct 2015 20:27:09 +0100, D. St-Sanvain wrote
(in article ):

is "G-52-15" a test registration ?
I don't remember seeing one before

Yes, it indicates an aircraft which does not have a full UK Certificate of
Airworthiness. In this case, the G-52 part of the registration means the
Belfast is being modified by Marshall of Cambridge.