Douglas Jeffrey, a youth and children's work development officer in Edinburgh, was sent to see Hamilton in May 1988.
He visited him at a club Hamilton ran at Linlithgow Academy, after a complaint from a parent whose son signed up for, but did not attend one of his summer camps, and who was being pressed for money by Hamilton.
Mr Jeffrey told the inquiry in Stirling that he was "uneasy" about Hamilton, who in March shot dead 16 pupils and their teacher at Dunblane primary school before killing himself.
Based on his investigation, a report recommended Hamilton's club be deregistered, but he said yesterday: "We did not have enough hard evidence ... to withdraw the let."
Hamilton's club was discontinued at that venue anyway as the council needed the facilities. Lothian region only stopped the letting for good after finding out that Hamilton was being investigated by police about an incident at a camp.
Hamilton waged a campaign against the policeman who compiled a critical report on the camp at Loch Lomond after parents complained over conditions at the camp, and at the way Hamilton "chastised" the boys, smacking them across the bottom with a table-tennis bat.
PC Gunn, who has been exonerated by the inquiry, said he visited the camp on 20 July 1988, and found conditions poor, and the boys running around without trousers; Hamilton said jeans would get wet as the boys played on the shore.
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