A man has gone on trial at Carlisle Crown Court accused of plotting to “nobble” jurors in a hearing involving his criminal son.

William Liversage, 50, denies a charge of intending to pervert the course of justice. This relates to a case heard at the crown court in October, 2014.

It is alleged that Liversage covertly filmed jurors with a camera disguised as a mobile phone while sitting in the public gallery during a drugs trial.

The defendants were his son and two other men – all were later convicted and jailed for conspiring to supply £1 million worth of heroin. The drug was seized from a car impounded by police and stored on a Carlisle industrial estate.

Prosecutor Brendan Burke, opening the case, said: “It is at that trial that the prosecution say this defendant – father of one of the men in the dock – decided to have a go at tampering with the jury.”

Liversage was arrested while travelling south on the M6 having attended court, and the trial was halted.

A covert camera, magnetic GPS tracker, another video recording device and seven face masks were recovered by police from his vehicle. There was video footage from outside the Earl Street building, in a toilet, on a public corridor and in court during the trial.

“We say very worryingly and very seriously he was sitting in court with a video device and at one stage he has got jurors on film,” said Mr Burke.

“If you imagine that – and how you would feel about that – you will get a flavour of the serious and dangerous territory that we are now into.”

The prosecutor alleged: “His plan was to meddle, interfere or, colloquially, nobble the jury.”

Referring to the face masks which were found in Liversage’s vehicle, Mr Burke asked: “Were they there for an innocent reason, given his son was on trial, looking at the wrong end of 10 years in prison? Were they intended, as the prosecution suggest, to be used by him and others – if others were involved – when the point of confrontation came with any individual juror who they had tracked down at home?”

Mr Burke stressed that no jurors in the trial had been approached or contacted.

Liversage, of Birkenhead, told police he was innocent and had no plans whatsoever to interfere with the jury.

The trial continues.