Jim Armitage: London's property developers are looking north for the best deals

To children’s charity Variety’s fundraiser at No. 10 and Albert Roux’s place nearby.

More than a smattering of London’s wealthiest property entrepreneurs were there — at one stage holding hands to sing “That’s Amore” at the behest of the Dean Martin-crooning MC.

The mood among the developers was ebullient — and why not when the capital is booming?

But there were concerns in some quarters that London office prices were, in the lingo, “a bit toppy”.

One, who’d invested solely in London for decades, got on the train two years ago to the regional cities of Sheffield, Manchester, Birmingham, York and Leeds.