The best thing about Senior Son being away from home is that I don't know what he's getting up to. Believe me, this can only be a good thing. Okay, I've got a pretty good idea - he forgets that I, too, was once a 19-year-old student - but, apart from the occasional telepathic tug at the heart at two in the morning, I can go about my daily life pretty much unperturbed.

Though there are odd moments, like the time I'd forgotten he was going away for the weekend. He was on the mobile and I pictured him in his room in his very swish hall of residence in Manchester. "Where are you?" I asked.

"On a train at Watford Junction," he replied. Of course.

The problem is that when they're based at home you KNOW when they're out 'til four in the morning....or out in the car in icy weather...or in a foul mood after an odd phone call...or looking glassy-eyed.

And you don't sleep...

Not that I ever wait up for them to come in. I've long since given up that trick or I'd be tottering round like the undead. But, as when they were babies, you can never quite switch off completely. We leave the light on downstairs and it creeps dimly round the edges of our bedroom door. So, even with half an eye open, I can tell if they're back or not. If the light's off, I zonk back into deep sleep. If it's still on, my sleep is never quite so deep and refreshing.

Last time Senior Son was home he came in at two o'clock on Saturday morning - quite early by his standards, so I had a good few hours sleep. He was out again on Saturday night. He was only going to Richmond, he said, would probably be home, but not to worry if he didn't make it.

At 6.30am the light was still on. His bed was empty, but I didn't panic. He wouldn't be back 'til lunchtime now, so I just got myself a cup of hot water and went back to bed.

I was lying there in the very grey light of dawn, when I heard something strange downstairs. I thought I'd heard the door open quietly. Then there were noises to make my heart thud in fear - a terrible soggy swishing, as if something dark and terrible was shuffling across the kitchen floor...

Senior Son had decided to walk the five or six miles back from Richmond. Daft enough in the dark and on a main road. But at some point, he'd decided to take a short cut across a field. (This was just before foot-and-mouth.)

He had, of course, fallen in the mud. And how. He'd lost his trainers in the morass and had clearly spent some time groping round trying to find them. He had thick wet mud, caked to well above his knees and generously spattered all over the rest of him. Thank goodness no one saw him or he'd have probably been mistaken for a Yeti and shot on sight.

I never found out exactly why he'd walked home. Something to do with too much lager and too few taxis, I suppose. But we managed to get everything washed and clean and dried again before he went back to Manchester that evening.

He rang to say he'd arrived safely. That night I slept like a log.