A Tory MP's aide was thought of as an "idiot'' by colleagues, despite being appointed to ensure strict spending limits were observed in the key 2015 general election battle for South Thanet, a court has heard.

MP Craig Mackinlay, 52, his election agent, Nathan Gray, 29, and party worker Marion Little, 63, are alleged to have "simply abandoned'' expenditure rules set by law to see off the challenge of the-then Ukip leader Nigel Farage.

Mackinlay, an accountant by profession, was elected to Parliament for the first time on May 7, 2015 after he won the seat with a majority of about 2,800 in an electorate of 70,000.

But his victory could have been voided if up to £66,600 of undeclared spending on staffing, accommodation, advertising and other expenses had been included on deliberately inaccurate expenditure returns, a jury was told.

Prosecutors allege Mackinlay, Gray and Little were complicit in submitting false expenditure declarations.

Southwark Crown Court has heard that Gray was employed by Conservative campaign headquarters (CCHQ) as Mackinlay's campaign manager from November 2014.

Experienced Tory campaigner Anthony Salter told jurors he did not know how Gray had come to take on the responsibility of acting as election agent and agreed that the role was "totally beyond him''.

"I didn't consider he had the appropriate training, skills and expertise,'' he said.

"I wanted somebody with the proper training and expertise to oversee (the expenditure returns) and make sure we didn't make stupid mistakes.''

"For some in the office there was a general perception he couldn't put his trousers on in the morning without the help of someone else..." - Trevor Burke QC

Mr Salter was the voluntary chairman of the local Conservative campaign team until the end of March 2015, when he bowed out after Little had "taken over'', he said.

Trevor Burke QC, defending Gray, suggested his client was "regarded in the office as an idiot'' by colleagues, who talked about him behind his back.

"For some in the office there was a general perception he couldn't put his trousers on in the morning without the help of someone else,'' he said.

Mr Salter agreed it had been expressed to him later, but added: "I do think it is unfair he's been pilloried for not being up to the job he's got no qualifications for.''

Declared spending on the campaign came in under the strict £52,000 limit set for the constituency, but prosecutors allege up to £66,600 was not declared.

Prosecutor Aftab Jafferjee QC said the spending limit for the long campaign - which ran from December 19, 2014 until March 29, 2015 - was slightly more than £37,000.

For the short campaign, between March 30 and May 7, 2015, the limit was slightly more than £15,000.

Mackinlay’s long return showed spending of £32,661.26 and his short return was £14,833.77 - both within the limit.

But Mr Jafferjee QC said: “It’s the prosecution case that neither of those declarations as to expenditure, the long return figure and the short figure, were true.”

He added: “Each of these three defendants were complicit in advancing these false declarations and in addition, the signature purporting to be Nathan Gray’s, the election agent on the long return, was not his.

“He had effectively permitted someone to forge his signature on that return.”

Tory official Victoria Carslake was the line manager of Gray at the time and told the court she "wasn't aware at all'' that his signature had been forged on an election expenses form.

She collected documents from Gray on June 11 which she took to South Thanet so the expenses returns could be filed on time.

She has denied any knowledge of the alleged forgery.

Trevor Burke QC, defending Gray, said: "It's a forgery, that is not Nathan Gray's signature.

"Someone has attempted to copy Nathan Gray's signature, and it's not a bad attempt some might think.

"But an expert tells us it's somebody other than him attempting to copy him.''

Mrs Carslake replied: "It's the first I've heard of such a thing.''

Mr Burke continued: "An explanation for this may be that the original (document) Nathan Gray gave you had been somehow misplaced or lost and as the final documents were being compiled for submission there was a realisation that it was a declaration short.

"And there was an attempt to forge Nathan Gray's signature on the long campaign declaration.''

Mrs Carslake said: "If that's what happened I wasn't aware of it at all.''

In a police interview, Mackinlay, who had been in politics for more than 20 years, attempted to "distance himself from Conservative campaign headquarters staff and volunteers drafted in to help with his campaign'', the court heard.

But the prosecutor said he was "fully aware'' of their assistance to him.

The court heard Mackinlay, Gray and Little had been warned about breaching spending limits in an email sent by Mr Salter on February 18.

"We're getting perilously close to hitting our legal limits, both for the long and short campaign,'' he wrote.

"I take on board your concerns that we face the real prospect of a legal challenge from Farage if you make the smallest slip up.''

Mr Salter told jurors he was concerned about breaking the law but explained to jurors he also raised the matter in disagreements with CCHQ over how money was spent as part of the ongoing friction between local Tories and central office.

The court heard the Conservative Party put extra resources into the campaign to win the Kent seat because, prior to the EU referendum, Ukip's support was on the rise.

South Thanet party chairwoman Lynne Connolly told the court Mackinlay would have been too busy to look at the expense submissions.

She also revealed how the Conservative Party's central office did not want Mackinlay to fight the election, telling how she rejected its request for an all-woman shortlist.

Mackinlay, from Ramsgate, denies two charges of making a false election expenses declaration under the Representation of the People Act 1983.

Gray, of Hawkhurst, Kent, denies one charge of making a false election expenses declaration and a further charge of using a false instrument under the Forgery and Counterfeiting Act 1981.

Little, of Ware, Hertfordshire, denies three counts of intentionally encouraging or assisting an offence under the Serious Crime Act 2007.

All three are on unconditional bail.

The trial, which is expected to last until December, continues.