For five hours the Victorian bleakness of the 'Bar-L' - scene of rooftop riots five years ago - was transformed by streamers and balloons as the expression 'detained at Her Majesty's pleasure' took on a new meaning. Even the weather was not allowed to spoil festivities. When it started raining, everyone just piled into the prisoners' gym, kitted out with a bouncing castle and a disco.
While a Radio Clyde disc jockey kept the requests coming, Pat Doogan cradled his three-and-a- half-month-old son Taylor, born three days before he was jailed for driving offences. Doogan, a binman from Kilmarnock in Ayrshire, was able to spend just one day with his son before starting his year's sentence.
His daughters, Patricia, 7, and Ashley, 3, were also close at hand. Had he any qualms about bringing his children into the prison at such an impressionable age? 'No way, I would never have passed up this day,' he replied. 'Besides, they don't really see the prison way of life. They come in here and it's just like a fete.'
But it wasn't Fun Day for everyone. The privilege was extended to just 40 of the 590 inmates, all Category C prisoners who pose little risk of escaping or are no threat to the public. 'Okay, it's just one afternoon out of 365 and it involves only a small minority of the inmates,' the assistant governor, Allison McWilliam, said, 'but one-offs are a good starting point in improving family contacts.'
Mrs McWilliam, who took along her own seven-month-old daughter Cally, added: 'This should be a regular feature of prison life, but we have to be sensitive. It might not seem a big deal to bring in these kids and let them play on a bouncing castle, but there is sometimes a reluctance to do things like this, from people who are paranoid about security.'
Staff in Scottish prisons have been under increasing stress since a number of warders were taken hostage in a series of rooftop riots in the late-Eighties.
But suspicions have gradually melted and a new, more liberal, regime has slowly been built up at Barlinnie, an establishment which caters mainly for prisoners serving short sentences. Most of those invited to yesterday's festivities are serving less than 18 months, most for driving offences.
Normally, family contact is restricted to two half-hour visits a month. Prisoners and their wives complain that such visits are rendered virtually worthless by the tight time-limit and lack of privacy. 'You can't hold your children like this at a visit,' Matthew Tullan said, balancing his 17- month-old son Matthew on his knees. 'They always tell you to take him down off the table.'
Like many who work in the prison service, Mrs McWilliam believes that wives and children are the 'forgotten victims' of the penal system. Organising yesterday's Fun Day was one small way of showing that their plight is not always forgotten. One of the youngsters summed up their verdict on Fun Day with a fine Glaswegian phrase: 'Pure dead brilliant]'