The go-ahead for the plant, which is expected to generate about 7 per cent of the UK's electricity needs and operate for 60 years, was confirmed in July but negotiations were still ongoing with French energy giant EDF about the exact funding arrangements with the UK Government.
The new plant will be built next to the existing Sizewell B, which is still generating electricity, and Sizewell A, which has been decommissioned.
In one of his last policy speeches as Prime Minister, Johnson said: “We need to pull our national finger out and get on with Sizewell C.
“That’s why we’re putting £700m into the deal, just part of the £1.7bn of government funding available for developing a large-scale nuclear project to final investment stage in this Parliament.
“In the course of the next few weeks I am absolutely confident that it will get over the line.”
The announcement comes in the wake of record high energy prices in the UK, which is expected to cause significant...