The Liberal Democrats will this week call for the “super-rich” to be taxed more heavily, citing new polling evidence that suggests the public would support what amounts to the most redistributive tax policy put forward by any main party.

Vincent Cable, the party’s Treasury spokesman, wants private equity chiefs and non-domiciled executives to help fund a 4p cut in the basic rate of income tax, a move aimed at winning favour among middle-class and poorer voters.