AdamG,

The occassional RN deployment to our northern waters to "meet & greet" a Russian vessel sometimes gets media coverage. We no longer have any maritime patrol aircraft, so a ship is sent.

IIRC last year and early this year a larger Russian vessel appeared and no RN warship was despatched until too late. It may even have anchored during a storm near UK territorial waters. The UK claims a twelve mile limit (except in a few places). Search Google on russian warship moray firth.

A lot of this activity is media hype, for many reasons, but to my knowledge none of the scrambled aircraft and ships actually respond to a Russian plane or ship actually in UK territorial waters.