What definition of area?
(a) If it is all that touches the ground but no more - i.e. (all UK within the boundaries of London and Scottish FIRs) minus (all class G at ground/sea level) it is one answer - I think the smallest number it could be.
(b) If it it (a) plus any CTA and TMA airspace, it gets bigger.
(c) If it is all lower level airspace below FL245 including all airways, it is bigger still.
(d) if it includes all CAS above FL 245, it is "(all UK within the boundaries of London and Scottish FIRs)" isn't it? i.e. the whole lot.
By the way, I am ignoring in the above - except in (d) - isolated ATZ's and MATZ's, but I assume that even in (a) all "isolated" CTR's would be included.
If that is not what Billy means, where am I going wrong?
Which definition does NATS use in its website figures quoted above?