The heroin was to be placed inside a legal-style envelope

Justin Cameron, 30, of Stonehouse, Plymouth, Devon, was sentenced at Exeter Crown Court after being convicted at an earlier hearing.

He was told by Judge Iain McIntosh: "This was a very devious, well thought out scheme to avoid the security of the prison and get serious class A heroin into the prison."

Cameron's defence counsel, Nick Lewin, told the court his involvement covered a very short time span "a matter of hours in terms of his direct involvement".

Legally privileged

Still awaiting sentence is 39-year-old Trevor Heath, of Commercial Road, Exeter, who admitted conspiracy and gave evidence for the prosecution.

Another former prison inmate, said to have masterminded the scheme to get the drugs into Exeter prison in January last year, jumped bail before the trial and is on the run.

The judge ruled he could not be named.

Prosecutor David Evans had told the jury that the "ingenious scheme" involved hiding wraps of heroin between two glued-together legal documents, concealed among others.

They were to be put inside a legal-style envelope which would be stamped indicating it was legally privileged documentation unlikely to be examined by prison staff.

Smuggling 'kit'

The jury heard Heath picked up Cameron when he was released from Exeter jail on January 25 last year.

On the night of January 25 police went to Heath's room at the hostel where he was then living, and under a duvet found a "kit" for putting together a heroin smuggling package, said the prosecutor.

There was a stamp, ink pad, correction fluid and A4 envelopes.

Underneath a speaker in the room was found an envelope containing legal papers, two of which had been stuck together to hide 1.04 grammes of heroin.