ALL of his life Thomas Hamilton bore a grudge against society, a grudge that erupted in his killing frenzy at Dunblane Primary School. The bald killer never accepted being drummed out of the Scouts 20 years ago and made it his mission to make society pay.

It seems that from cradle to grave he always blamed other people for his misfortunes. While nothing can explain the crazed and cold-blooded way he ended his life, it had always been a strange one with bizarre beginnings.

To the outside world, the young Glasgow-born Thomas was a normal child with an elder sister and elderly parents. But the family hid a dark secret. For the young woman who played the role of his big sister was in fact his natural mother.

And his elderly parents, who legally adopted Thomas, had years before adopted his natural mother.

The confusing family history dates back to 1931 when the gunman's natural mother, Agnes, was born illegitimately. In the days when an illegitimate child was a shame to the whole family, Agnes's embarrassed mother, Rachel Hamilton, a widow, gave her baby daughter away to her late husband's family.

Rachel's childless brother-in-law, James Hamilton, and his wife, Catherine, took young baby Agnes into their home and legally adopted her. For 19 years Agnes stayed with her adopted parents at their Glasgow home until she met and fell in love with bus driver Thomas Watt, 21.

Thomas and Agnes married in Bridgeton Church, Glasgow, in December 1950, and within two years the couple had a son, also called Thomas. But when the little boy was just 18 months old, his father fell in love with a bus conductress, Margaret McGill, and turned his back on his son and wife.

Distraught Agnes and the baby moved into the home of her adopted parents in 1954. Her adopted parents did all they could to help and in the spring of 1956, when Thomas was aged just four, they took the unusual step of adopting her son.

How old he was when he was told his real identity is unclear.

Other pieces in the jigsaw that make up the mind of the depraved killer started to fall into place in the early 1970s. It was then he first began to run his so-called youth clubs. Even then, in the early days, there were doubts about his suitability to have such work.

His appointment as a volunteer assistant in Stirling taking children on outings involving Scouts was withdrawn after two weekend camps in Aviemore in 1974.

A spokesman for the Scout movement said:``During the first weekend Hamilton claimed he had booked a hostel for the boys in Aviemore, but that was untrue. He had slept in the back of the van with eight boys. This only came to light when the van froze up and the children had an uncomfortable night.

``On the second occasion they were digging snow-holes and got extremely wet and cold.''

The spokesman said that at the time there were no allegations of a sexual nature and the complaints centred on his leadership qualities.

He had no convictions for sexual offences but had been cautioned by police 18 months ago after being caught in a compromising position on Edinburgh's Calton Hill, a well-known haunt of the gay community.

A former member of Hamilton's boys' club yesterday told how the killer patrolled the streets of Dunblane with a pistol tucked in his trousers.

Mr James Finney, now in his 20s, told how he frequently saw Hamilton carrying his gun in the streets.

Mr Finney said: ``Recently I saw him a few times on the train at Stirling and he was carrying a gun. He was wearing a jacket that was quite tight and I could see the handle of the gun sticking out of the jacket.''

Mr Finney, who says he now wishes he had reported his sightings of Hamilton to the police, said he thought the killer's gun carrying was common knowledge.