A member of a paedophile gang which infiltrated a breakaway Scout association and may have abused up to 300 boys was jailed for four years yesterday.

Scout leader Dennis Ward, 66, who took part in the ''systematic abuse'' of a vulnerable 13-year-old boy, is seriously ill and has been told he has a life expectancy of no more than 24 months.

The gaunt, white-haired pensioner, from Plymstock, Plymouth, helped run the 22nd Waltham Forest Baden-Powell Scout Group, and was a member of a network believed to have preyed on youngsters as young as eight for well over 30 years.

He showed no reaction at London's Snaresbrook Crown Court as Judge David Radford said that his behaviour had helped undermine the reputation of the Scout movement.

Earlier Mr Mark Gadsden, prosecuting, said that Ward's victim joined the Baden-Powell Scouts Association - which broke away from the Scout Association in 1970 - when he was 11, and at a time of ''particular vulnerability'' as far as problems in his family were concerned.

He was almost immediately targeted by Ward's co-conspirator and fellow Scout leader Douglas Braithwaite - who died before he could be brought to justice - and subjected to ''systematic and organised abuse''.

Mr Gadsden said: ''He had been thoroughly corrupted by the time he was 12 years old . . . and having been so comprehensively corrupted, Braithwaite was thus in a position to introduce him to other members of the paedophile ring, including Ward.''

At the time the youngster did not know Ward by name, but recognised him as a Scout leader at the troop's regular Monday night meeting and as someone who also played the accordion at a church.

Mr Gadsden told the court that the youngster had described being taken to Braithwaite's flat in either June, 1994 or 1995, and subjected to prolonged and serious sexual abuse. There were also two further occasions when Ward abused him, both times again in front of Braithwaite.

Mr Stephen Fiddler, defending, said his client, who had no previous convictions, was now ''genuinely remorseful'' and ''very very genuinely disturbed'' to think of the effect his actions may have had on his young victim.

The judge told Ward: ''What you did . . . has besmirched the good name of the Scout movement, making it harder for genuine and selfless Scout leaders to fulfil their role without the risk of parental and public suspicion and concern.''

Although he had pleaded guilty to one count of conspiracy to commit buggery, this had come late in the day and earned him little credit.

While he had heard everything that had been said about Ward's failing health, it was not for him to reduce the sentence because of it, the judge said - that was a matter for the Home Secretary.

The court heard that three other men - all Scout leaders - who have admitted their part in the paedophile ring's activities, will be sentenced later this month.

They include Brian Turner, 60, known as The Chickenmaster for his ability to lure children into his clutches. Turner, who was initially due to have been dealt with yesterday, was part of the ''dirty dozen'' paedophile ring which was smashed in the 1980s.

Four of them, including Sydney Cooke, were convicted of the manslaughter of 14-year-old rent boy Jason Swift in 1985.

Police believe Turner may have introduced the teenager to Cooke, who was jailed for 19 years and recently freed amid public outrage.

The investigation, jointly carried out by police and the National Society for the Prevention of Cruelty to Children, spanned five police forces, included Holland, France, Spain and Belgium, and uncovered a vast library of child pornography. The material was discovered at the west London home of Robert Kearns, 50, one of those due to be sentenced later.

One of the videos seized showed a boy sobbing as he was first tortured with electrodes and then further abused.

At least 10 other suspected members of the gang, teachers and social workers among them, are understood to be part of an ongoing investigation.