It might also be worth pointing out that the UK does not have an integrated ATC system for civil data as such and in order to identify who is working certain aircraft each unit is assigned certain groups of codes.
On the airways system the single UK computer is used by all and thus you keep the code from start to finish. Leave the airways and each unit will give you a new code simply because they have to in order to show other units that they are talking to you.
Many other places have an integrated system and you keep the same code from start to finish and the ATCOs simply right click and change the return data label to show who is working the aircraft.
Mode S will change all that......so what is the UK plan for ensuring that radar units are aware of who (if anyone) is working G-ABCD plodding along about to get in front of the IFR (RAS) inbound?
Regards,
DFC