Surely early payment penalties would come into play with such over payments as well?
How can someone with a 500k mortgage and earning enough to pay £1900 a month not work this out for themselves?
Or is he the rich/low IQ type?
I doubt very much that even the best blagger could sustain a 6 figure salary job for 3 years without at least someone questioning it.
Wouldn't that be only after he has exceeded the capital gains tax limit of £11k?

Pretty sure most mortgages (mine does at least) have an over payment limit of 10% per year.