‘All individuals in our society will have a chance to own some shares in the future of these banks.’

The Tories hope a populist share sell-off will breathe excitement into an election campaign where voter-friendly tax breaks are in short supply. The public would be offered the chance to buy up to a few thousand pounds worth of shares at a discounted rate. Further discounts could be offered to the poor, the young and parents investing for their children.

The share purchases could be handled through the Government’s existing Isa saving scheme, making any profits tax-free.

Critics said it might take years to ready RBS and Lloyds for sale because both are still losing billions. They pointed out that shares in both are available on the open market at a 30% discount to the price paid by the Government when it rescued them.

Liberal Democrat Treasury spokesman Vince Cable said the plan represented ‘Tory electioneering at its most cynical’. He said it would also reduce the final return to the taxpayer.

Cable added: ‘The nationalised and semi-nationalised banks should be reprivatised when the conditions are right to maximise taxpayer return. Selling shares off at a discounted rate will not achieve this.’

How would a shares sell-off work?

Details of how a bank shares sell-off would work are sketchy. For example, the Conservatives did not clarify whether they would simply be selling off the taxpayer owned part of the banks or issuing even more shares.

It’s all very well saying it could be modelled on the privatisation of British Gas, with its Tell Sid adverts that encouraged people to invest, but that was the sell-off of a successful utility, not the return to private hands of a couple of failed banks.

Profits could be tax-free, with an investment model based on the Isa investing system, but what would happen to existing shareholders in the banks and their shares?