As I speak a baloon is................
just passing over Banstead at about 1000', the extreme South East corner of the London TMA. It is the "SKY" baloon and is 'on course' to overfly Biggin I reckon.
How it managed to traverse the middle of the Gatwick and London zones I have no idea, but I take my hats of to them.
A little surprising at this time of day in this area I must say.