A former Ukip and Conservative MP has been found guilty of tricking elderly constituents into signing electoral forms backing local candidates.

Bob Spink, who served as Tory MP for Castle Point in Essex for five years before defecting to the pro-Brexit party in 2008, was found guilty at Southwark Crown Court of four counts of submitting false signatures on nomination forms, a type of electoral fraud.

Spink, 69, of Benfleet in Essex, showed no emotion as the jury foreman returned majority verdicts on all four counts he faced. He will be sentenced in the new year.

James Parkin, 39, Ukip’s election agent at the time, was found guilty of two counts of the same offence, and found not guilty of three. He had already admitted two counts.

Judge Ian Graham said: “These types of offences are taken very seriously.”

Jurors heard Spink tricked “elderly and infirm” voters into signing the forms in April 2016, without making it clear what the documents were or which party he represented.

The court heard people in Spink’s constituency signed forms believing they were petitions, and having no idea they were supporting the Ukip candidate in the Castle Point Borough Council elections.

Spink said everything was above board, that residents knew what they were signing, and that he only introduced the topic of the local elections once he had had gained their support for his campaign to become a police and crime commissioner (PCC).

None of the candidates included in Spink’s deception won a seat on the council, although a handful finished runner-up, the court heard.

Outlining the case, prosecutor Tom Nicholson said: “Did he disarm voters by talk of Europe, police, his PCC nomination, the need to obtain 100 signatures, and their desire for more police on the streets?

“Did he properly inform them which party he was in fact representing?

“Did he use what we would suggest was a casual and misleading approach on the doorstep?

“You will hear from quite a number of witnesses whose evidence, taken together, suggests just that.”

Mr Nicholson said there was “no issue” with the 100 signatures obtained by Spink for him to stand as a candidate in the PCC election, during which the defendant was narrowly beaten by a Tory rival.

The court was told the police investigation into the Castle Point Borough Council elections began before polling day when a resident called Rupert Duke discovered his name had been added to a nomination form for a Ukip candidate called Lucy Parkin - who was a relative by marriage of the younger defendant, of Canvey Island in Essex.

Mr Duke told police he had never signed the form as he was a Tory voter “and would never have had anything to do with Ukip”.

Jurors deliberated for 12 hours and 52 minutes before returning the verdicts on all counts at the end of the three-week trial.

Judge Graham adjourned the case for sentencing at Basildon Crown Court on January 5. Both men were released on bail.