Sore at missing out on the £50 million pad up in London's own Billionaire Row that was sold last month? Well, here's the good news - another one's just come on the market. Steel tycoon Lakshmi Mittal has decided to up sticks from Bishops Avenue in Hampstead, after Barrat Homes were given permission to build a block of luxury flats right next door. Britain's richest man apparently didn't fancy contending with one of the......