Well it would have been easier if they had just got a school compass and pencil, stick the point into Stanstead and drawn a circle of 13nm and then written "TMZ" in the circle rather than:
515416N 0002653E thence anti-clockwise by an arc of a circle 8 nm radius
centred on 515306N 0001406E to 520104N 0001503E - 520517N
0002124E thence clockwise by an arc of a circle 13 nm radius centred on
515306N 0001406E to 515828N 0003314E - 515416N 0002653E.514508N 0001309E - 514055N 0000652E thence clockwise by an arc of
a circle 13 nm radius centred on 515306N 0001406E to 514550N
0000316W - 515146N 0000006W - 515155N 0000120E thence anticlockwise
by an arc of a circle 8 nm radius centred on 515306N 0001309E
to 514508N 0001309E.
Just my humble opinion. In fact draw one great big circle centred on Buckingham Palace of radius 20/30/40 nm (delete as nescessary) and done the same thing would be fine by me because by the time we've finished with TMZ's there will be bitty, disjointed TMZ's littering the SE and we'll have numerous coordinates to wade through, and the resulting busts of course.