The agent overseeing the Conservative election campaign in South Thanet nearly quit because he was feeling miserable and felt ineffective.

Nathan Gray told a court he had come close to resigning just as the hotly contested election entered the final stages.

The 29-year-old is one of three defendants on trial amid allegations the party exceeded election spending limits during the battle for the South Thanet seat and that had the spending been property recorded, it would have been in breach of those limits.

Giving evidence at Southwark Crown Court, Gray said he had considered leaving.

"I was pretty miserable...there was a certain weariness and I felt I was not being effective," he said.

However, he decided he would not "bow out" and continued with the role.

"I felt I had an element of wanting to stay to keep the momentum going."

Asked earlier in the hearing how he had become party agent, he described how no one else was interested.

"Nobody else seemed interested...it fell into my lap," he said.

Asked if he had known what an election agent did, he said: "No".

Asked if he had any proper training to become agent, he replied it was limited to advice about how to complete candidates' nomination papers.

During the hearing, he was led through a series of emails involving details of exchanges about campaign spending between himself, fellow defendant Marion Little and constituency officials.

He said he had no role in authorising some of the more controversial spending such as on battle buses and leaflets depicting the election as a two horse race between Mackinlay and then Ukip leader Nigel Farage.

He said when he raised questions about some expenditure, he was told it fell into national rather than local spending.

He had not asked how the party was meeting the costs of putting him up in Thanet during the election campaign.

That had been arranged because he was finding it difficult to get to campaign meetings from his home in Hawkhurst.

Questioned by prosecution counsel Aftab Jafertee if he felt there were some expenditure on Mr Mackinlay's expenses which had not been authorised by him, he said: "In hindsight, there have been some items that have been omitted from the return."

Earlier, the court was read two witness character statements submitted in support of Mr Mackinlay.

One was from John Weir, former chairman of the North Kent magistrates board, and Mackinlay was described as an honest and fair-minded and popular person in the magistrates bench.

Mr Mackinlay, 52, his agent Mr Gray, along with senior party worker Marion Little, 63, all deny deliberately filing false expenditure returns after the 2015 general election.