Hopefully the RN can work their way up to this challenge - being able to provide a recognised surface picture only, on an area about the size of a large lake in an uncontested and benign area of operations.
If the RN get the hang of it they could look to achieve a surface picture of say, the south coast. Clearly this capability will take a few years and probably best to ignore sub-surface or the air domain.
Beyond that, as a stretch target, the RN could try and have a loose idea of the surface picture around England, with a potential 'surge capability' to the inshore areas of Scotland and Wales.
Rule, Britannia! Britannia, rule a few waves, and one day perhaps even inflatables.
Still, credit to the Boarder Force, Police Service, Coastguard, Typhoon Force, E-3D, Sentinel, Poseidon and Atlas for all having a go at maritime operations.