Police have confirmed they will be taking no action over allegations of overspending by the Conservative Party in a by-elections row.
Channel 4 News said it had obtained hundreds of pages of receipts which suggested the party broke electoral rules in three 2014 polls in Newark, Clacton, and Rochester and Strood.
The Tories defeated Ukip in Newark, but went on to lose the other two by-elections that year.
In relation to the claims in Newark, Nottinghamshire Police Chief Constable Chris Eyre said it was "too late" to bring any prosecutions for alleged election expenses' offences for the poll which took place on June 5, 2014.
In a letter to police and crime commissioner Paddy Tipping, Mr Eyre said there was a 12-month statutory limit in prosecutions brought under the Representation of the People Act, the law which governs elections.
He wrote: "The purpose of this limit [12 months] is to ensure finality in elections and as such no proceedings could be brought in this case.
"I hope this reassures you of the current legislative framework and the powers available to the police in a case such as this."
As the financial return for the poll was made on July 4, 2014 the limit has passed, he said.
Mr Tipping, former Labour MP for Sherwood, had written to Mr Eyre to "remind" him of the "seriousness and importance of considering the matters closely".
In his response, Mr Eyre said he had discussed the matter with the Crown Prosecution Service and other police forces where similar allegations have been made.
Mr Eyre noted there have been recent cases that "demonstrate attempts to circumvent" legislation by way of common law, such as conspiracy to defraud, but these "have been held to be an abuse of process and as such have been discharged".
Kent Police said it will also not be taking any action in relation to the alleged overspend for the Rochester and Strood by-election for the same reason, after taking legal advice.
A spokeswoman for Essex Police said the force had not received any complaints about any alleged breach of electoral law relating to the Clacton poll.
A party spokesperson said: "All by-election spending has been correctly recorded in accordance with the law."
Campaign spending in by-elections is limited to £100,000 for each party.
Channel 4 claimed undeclared receipts showed the Conservative Party booked 59 rooms at Kelham House Country Manor Hotel, in Newark, during the "regulated campaign period" when the spending rules are in place, from May 2 to June 5, 2014, costing £4,209.30.
It is also alleged the party booked 125 nights at the Premier Inn Newark, totalling an estimated £6,250 — none of which were included in the party's declarations — which would meant a £6,650.28 overspend.
The majority of the rooms — according to the investigation — were booked under senior campaign organiser Marion Little's name using her home address.
The channel also said it had uncovered £56,866.75 of undeclared hotel bills in Rochester and Strood, which would have taken the party £53,659.83 over the £100,000 spending limit.
It found bills totalling £26,786.14 in Clacton, which would have taken the party £10,835.36 over the limit.
In 2014, Conservative candidate Robert Jenrick won the Newark by-election — called after MP Patrick Mercer stood down following a cash-for-questions scandal — with 7,403 more votes than nearest rival Roger Helmer, for UKIP.
During the by-election campaign, David Cameron visited the town four times, as UKIP members battled for their first parliamentary seat.
Mr Helmer said: "I'm not in favour of a re-run of the election — I feel the public perception would be of a 'bad loser'.
"I do though feel the Conservatives have an awful lot of explaining to do."
Mr Jenrick retained the seat in last year's general election.
Tory defector Douglas Carswell won Clacton in the 2014 by-election for UKIP — becoming the Eurosceptic party's first MP — winning again in 2015.
Another Tory defector, Mark Reckless, took Rochester and Strood for UKIP in 2014, but lost in the 2015 poll to Conservative candidate Kelly Tolhurst.
Mr Jenrick told BBC News he was "very confident" his election expenses were compiled "in complete compliance with the law".
"The allegations that were on Channel 4 News are, as far as I can see, completely unfounded," he added.
A spokesperson for Channel 4 News said: "We note the comments from Robert Jenrick MP regarding our investigation into election expenses.
"The Conservative Party are yet to explain why hotel accommodation costs for campaign workers were not fully declared in three by-election returns.
"We stand by our journalism and welcome the MP for Newark on to Channel 4 News to discuss our findings at his earliest convenience."
However it emerged on Thursday (February 18) that the Conservative Party would face an investigation into its election spending in the battle to defeat UKIP leader Nigel Farage in South Thanet.
The Electoral Commission confirmed it would look into Tory spending following the investigation by Channel 4 News.
The Conservatives declared hotel bills costing thousands of pounds as 'national spending' meaning they were not counted against the spending limits of their winning candidate Craig Mackinlay.
The Electoral Commission announced it will look into whether the £14,000 bill should have counted within strict 'candidate spending' - sending Mr Mackinlay far over tight limits.
It has been reported that Kent Police will not pursue an inquiry into the claims at this stage.
But the force told Police Professional
: "If the Commission concludes that the spending should have been recorded as candidate spending then Kent Police will review this matter, if it is suspected that offences may have taken place in Kent."
The Electoral Commission said: "The Commission reminded Kent Police that the ability to investigate these allegations will end one year on from the May 2015 UK Parliamentary General Election.
"Unless the police apply to the Courts for an extension, which they are entitled to do under the Representation of the People Act (RPA), they will have missed the opportunity to investigate any allegations.
"Anyone found guilty of an offence under the RPA 1983 relating to candidate spending or the making of a false declaration in relation to candidate spending, could face imprisonment of up to one year, and or an unlimited fine."
Turning to its own investigation, added: "The investigation opened by the Commission today focuses on whether the Conservative Party met their reporting obligations under the Political Parties Elections and Referendums Act (PPERA) 2000."
It will examine whether the spending reported by the party in its 2015 UK Parliamentary General Election (UKPGE) campaign spending return, in relation to the Royal Harbour Hotel Ramsgate, was not national campaign spending and therefore should not have been included in the party's return.
The Commission will also study "whether spending on the Premier Inn Margate was national campaign spending and therefore should have been included in the party's 2015 UKPGE campaign spending return".