Prime minister David Cameron has insisted improvement work to the A47 will start during this parliament, quipping that he would get in the diggers himself if he had to.

On a pre-election visit to Norfolk before Christmas, Mr Cameron pledged £300m for work on the A47, with work due to take place during the next parliament.

But Highways England recently said it was likely to be five years before diggers could move in, with a further three years of construction work - prompting Norfolk's concerned MPs to demand that work gets under way more rapidly.

Mr Cameron, on a visit to Norfolk yesterday, insisted he had not made a rash promise when he said the work would start in this parliament.

He said: 'No, because we said we wanted to get going on the A47 and the money is there. We will do everything we can to start that as soon as possible.'

He said there would inevitably be a considerable amount of preparatory work but said: 'My understanding is that there is no delay and diggers will go in during this parliament.

'It should start before 2020 or in 2020 and we will do everything we can to keep the pressure on. I may have to get the diggers out myself.'

Mr Cameron also remained upbeat over the prospects of Norwich in Ninety - the long-running campaign to speed up trains between Norwich and London - a key part of the Conservative manifesto.

Recommendations from a task force which has been pressing for improvements - which includes £476m of infrastructure investment and new trains to be demanded in the next operator contract - were supported by chancellor George Osborne in the autumn statement.

But, in June, just after the Tories returned to power with a majority, south west Norfolk MP Elizabeth Truss revealed the Department for Transport had instigated a review of all rail work ahead up to 2019.

Network Rail admitted it had been 'overly optimistic' over its plans.

However, Mr Cameron said: ''On Norwich in Ninety, the most important thing was the launch of the competition for the franchise next year. We need better trains and infrastructure investment and I am confident that will happen.'

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