It's called "market forces" - and I'm surprised Vanguard don't charge more when you consider (a) how close to the square mile they are and (b) the prices charged to land in a far-flung corner of London at least 40 mins by cab from the CBD.
Good people at Vanguard. Very friendly and efficient.
That "landing unlicensed in a congested area" thing catches quite a few.........