The Government says much of the spending pledged represents new cash and includes committing over £500m to the development of mini nuclear power station technology.

This will support Rolls Royce and its other engineering partners including BAM Nuttall and Laing O’Rourke advance ambitious plans to build up to 16 mini-nuclear plants in the UK.

The consortium claims that up to 80% of the power station components would be made in factories in the Midlands and North of England, before being transported to existing nuclear sites around the country for rapid assembly inside weatherproof canopies.

Johnson will claim that the £12bn of government investment will leverage potentially three times as much from the private sector to create and support up to 250,000 green jobs.

His green plan also includes an already pledged £1bn of investment into making new and existing homes more efficient and quadrupling offshore wind power to 40GW.

Johnson said: “We will make the UK the Saudi Arabia of wind with enough offshore capacity to power every home by 2030.”

Around £240m will also be released to support building new hydrogen production facilities, with the promise of a town heated entirely by hydrogen by the end of the decade.

Another £200m will be invested in developing carbon capture initiatives.

His plan will also include a ban on combustion engine sales by 2030, with grants for electric cars

Johnson said the Government would invest more than £2.8bn in electric vehicles, lacing the land with charging points and creating long-lasting batteries in UK gigafactories and funding for charge points.

The sale of some hybrid cars and vans will continue until 2035.