A new Channel 4 documentary, "How to Get Filthy Rich with Gary Stevenson", has become the focus of a row over the millionaire trader-turned-campaigner's proposal for a wealth tax, which critics in the programme brand "absolute populist claptrap" and "disastrous". The debate matters because Stevenson is rumoured to have been approached by Andy Burnham's team to advise on financial policy, potentially placing his ideas near the centre of Labour thinking ahead of the former Greater Manchester Mayor's expected bid for the premiership.

Stevenson, 39, a former Citibank trader, proposes a 2 per cent annual tax on assets exceeding £10million, which he claims could raise up to £24billion a year for the Treasury. Critics warn it could instead drive £100billion out of the country as wealthy individuals leave, harming growth, investment and jobs, with one billionaire saying he would quit Britain if it were introduced. In a clip, Andrew Henderson, founder of Nomad Capitalist — a firm that helps the rich legally cut their taxes by relocating — accuses Stevenson of an "obsession with solving inequality", arguing the world will always be unequal.