Prosecutors say the case against Tory Craig Mackinlay remains open while their investigation into his election expenses continues.

The former South Thanet Tory is now the only person still under investigation, although prosecutors say no conclusion should be drawn from that fact.

A statement released at 11am said investigators had looked at files from 14 forces "in respect of allegations relating to Conservative Party candidates' expenditure during the 2015 General Election campaign."

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They said they "considered whether candidates and election agents working in constituencies that were visited by the Party's 'Battle Bus' may have committed a criminal offence by not declaring related expenditure on their local returns.

"Instead, as the Electoral Commission found in its report, these costs were recorded as national expenditure by the Party."

But, after reviewing the files it confirmed that no criminal charges had been authorised.

Video: Investigation remains into Thanet's Tory expenses

However: "One file, from Kent Police, was only recently received by the CPS, and remains under consideration.

"No inference as to whether any criminal charge may or may not be authorised in relation to this file should be drawn from this fact and we will announce our decision as soon as possible once we have considered the evidence in this matter."

Mr Mackinlay has persistently denied the claims, which focus on allegations that the party’s election expenses during the 2015 campaign in South Thanet were not properly reported to the Electoral Commission.

They concern the costs of battle buses used to bring in activists and hotel accommodation during a bitterly fought campaign in the seat where former Ukip leader Nigel Farage was trying to become MP.

Had they been, it is claimed they would have breached laws on the spending limits.

Mr Mackinlay was interviewed under caution for six hours about the claims as part of the police inquiry.

In an interview for KMTV’s Paul on Politics show recently, he shrugged off the suggestion the inquiry would overshadow the Conservative campaign.

“I have done nothing wrong and acted honestly and properly throughout the campaign so no, I'm not concerned at all,” he said.

The South Thanet Conservative Association has rallied behind its candidate, saying they continued to back him. In a statement on its website, the association said: "In response to recent media comments concerning the expenses incurred in the 2015 General Election by South Thanet MP Craig Mackinlay, the South Thanet Conservative Association wishes to reaffirm its strong support for Mr Mackinlay and his agent Mr Gray. We would also like to express our appreciation for Mr Mackinlay’s continued hard work in South Thanet."

The CPS statement in full

Nick Vamos, CPS Head of Special Crime, said: "We have considered files of evidence from 14 police forces in respect of allegations relating to Conservative Party candidates' expenditure during the 2015 General Election campaign.

"We considered whether candidates and election agents working in constituencies that were visited by the Party's 'Battle Bus' may have committed a criminal offence by not declaring related expenditure on their local returns. Instead, as the Electoral Commission found in its report, these costs were recorded as national expenditure by the Party.

"We reviewed the files in accordance with the Code for Crown Prosecutors and have concluded the tests in the Code are not met and no criminal charges have been authorised.

"Under the Representation of the People Act, every candidate and agent must sign a declaration on the expenses return that to the best of their knowledge and belief it is a complete and correct return as required by law.

"It is an offence to knowingly make a false declaration. In order to bring a charge, it must be proved that a suspect knew the return was inaccurate and acted dishonestly in signing the declaration.

"Although there is evidence to suggest the returns may have been inaccurate, there is insufficient evidence to prove to the criminal standard that any candidate or agent was dishonest.

"One file, from Kent Police, was only recently received by the CPS, and remains under consideration" - Nick Vamos from the CPS

"The Act also makes it a technical offence for an election agent to fail to deliver a true return.

"By omitting any 'Battle Bus' costs, the returns may have been inaccurate.

"However, it is clear agents were told by Conservative Party headquarters that the costs were part of the national campaign and it would not be possible to prove any agent acted knowingly or dishonestly.

"Therefore we have concluded it is not in the public interest to charge anyone referred to us with this offence.

"Our evaluation of the evidence is consistent with that of the Electoral Commission.

"While the role of the Commission is to regulate political finances and campaign spending, the role of the CPS is to consider whether any individual should face criminal charges, which is a different matter with different consideration and tests.

"One file, from Kent Police, was only recently received by the CPS, and remains under consideration.

"No inference as to whether any criminal charge may or may not be authorised in relation to this file should be drawn from this fact and we will announce our decision as soon as possible once we have considered the evidence in this matter."