The Northern Rock crisis, tax changes for non-domiciled UK residents, more onerous European rules and US regulatory improvements could combine to cast London off its perch as the world’s top international financial centre, according to a leading economist.

London has topped the charts among the world's financial centres in all three bi-annual research reports commissioned by the City of London since last year, but saw its lead over New York cut in the most recent report in March to just 0.9%.