The UK is lagging behind other developed economies by not broadening market access to private investors – a move which will make capitalism more popular, Mr Rolet continued.

“The exceptional demand for shares in businesses like Royal Mail Group has proven the appetite savers have for investing and in IPOs in particular,” he wrote.”We ask that this Budget takes the steps to ensuring that a private investor tranche becomes not an oddity, but the default choice for most companies as they IPO.”

The Summer Budget will be delivered on Wednesday July 8, and will include an increase in NHS funding until 2020, a new raft of austerity measures and an expected inheritance tax threshold raise to £1m. A new tax banning income tax, VAT or National Insurance rises before 2020 is also likely to be announced.

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