Don't forget 'Delegated Airspace'.
At the moment, a substantial chunk of the London FIR, (Swanwick's airspace), is delegated to EGPX. This is basically the area controlled by the former area control centre at Manchester. The Manchester sub-centre was originally planned to re-locate to Swanwick, but due to NATS budget considerations, and the plan to boost the Ayrshire economy, eventually moved to Scotland.
This airspace is the West 2 Local Area Group, and is the reason aircraft departing from EGCC are transferred to 'Scottish Control' on departure, and inbounds from the south call Scottish, prior to transfer to Manchester Approach Radar.