Ikent his faither. In fact, his old man was a Church of Scotland minister in Paisley when I was working in Easterhouse. To replenish our Christian Aid shop, I used to go out to Paisley to pick up some of the second-hand clothes that were kept in a garage beside the manse. In later years, he would tell me about his son, a young, unknown actor who was struggling to make a living.

Who am I talking about? Knock, knock. Who's there? Doctor.

Doctor Who? That's right. David Tennant, who was back on our television screens on Saturday, beginning a new series of the longest-running science-fiction programme of all time.

The young actor who lived from hand to mouth has morphed into a 36-year-old cult star. The 10th Doctor Who was voted "the coolest man on TV" last year, and was named "Scotland's most stylish male" - presumably not wearing clothes from the garage in Paisley - in the Scottish Style Awards.

On websites devoted to him, breathless girls post un-Presbyterian fantasies about waking up in bed next to the son of the preacher man.

David's father, Dr Sandy McDonald, one of the wisest men I know, is a former Moderator of the Kirk's General Assembly.

A fair number of children of clerics have made their mark in their chosen spheres. Van Gogh, for instance, whose dad was a Calvinist minister and a part-time spy.

Quite a few children of the manse have gone into public service of one kind or another. The roll-call includes Andrew Bonar Law, Lord Reith, John Logie Baird, John Buchan, Eric Liddell, Lord Steel, Lord Fraser, Douglas and Wendy Alexander, Michael Moore, Sheena McDonald and, of course, Gordon Brown.

Public service is reckoned to attract so many manse kids because of Presbyterianism's reputed moral seriousness and intellectual rigour. This is given credence by Gordon Brown's description of his father's influence as "the moral compass that has guided me through each stage of my life". (This is the kind of public phrase that can rise and bite one when the going gets tough.) Being brought up in a manse can be a trial. I'm not an expert on this - there's not a single drop of ecclesiastical blood in my family, and I was only in the parish ministry for 11 years - but I'm well aware of some of the hazards.

For a start, most manses are freezing, absolutely Baltic. Big old houses with high ceilings are impossible to heat on a stipend. Manse kids also have to put up with a procession of some of the weirdest people on God's earth traipsing through their home.

On the plus side, they are regularly exposed to passionate debate and offbeat, even crazy, experience.

Probably the most difficult thing for children of clergy is that they're often expected to be model Christians. School can be a particular trial, especially if father or mother is chaplain.

There can be taunts from teachers as well as fellow pupils; turning the other cheek may not be the best survival technique. Two of my children went to school in Easterhouse (yet the only place they were ever bullied was the holy island of Iona).

With such exposure to public scrutiny, it's understandable that quite a number of manse kids rebel against religion. When the teenage son of good friends of mine - the boy's father is a distinguished Church of Scotland minister - was having a haircut, he was asked by the barber what his father did.

Rather than admit he was a meenister, the lad said he was a joiner. And where does he work? Hillington industrial estate, said the sweating boy. By the time he had been shorn, he had invented a whole new CV for his dad.

From freezing manses to playground mocking to the weight of Presbyterian history - all character-building stuff - it's also not surprising that many manse kids go spectacularly off-message. For every Gordon Brown, there's a William Kidd. Son of the Rev John Kidd of Greenock, William took an interesting career path: he became a pirate. Found guilty of murder and piracy, he was hanged in 1701. His body was left to rot in an iron cage over the River Thames for two years. So let that be a warning to all would-be manse rebels.

Back to David Tennant. My stock has risen dramatically in the audience which matters most to me - my two small grandchildren. They can casually tell their astounded wee pals that their granddad actually knows Doctor Who's father.

They think I'm a Time Lord. I tell them that Sandy McDonald travels around in a used Tardis. Meanwhile, Gordon Brown sometimes wakes up in the morning wishing he'd become a pirate instead. A manse is a manse for a' that.