The car was loaded up with two suitcases, three boxes of toys, one blue teddy, three children and three packets of chocolate buttons to be opened only in case of dire emergency or tantrums.
'Do you think we've got everything?' I said to my wife.
This was our bi-annual road-trip up north to tour the grandparents.
Separating us was five hours of bumper-to-bumper traffic, at least two stops for the toilet, three screaming meltdowns in the back of the car, 250 miles of road and an ocean of effort.
But then the front door opened and all the exhaustion melted away because standing there were my children's grandparents beaming with happiness.
'Grandma! Grandpa!' the children shouted and in the next moment, the two generations were wrapped around each other.
It had been months since they'd last seen each other and they weren't planning on wasting another moment. First it was playing hide and seek with Grandpa. Next it was doing some gardening with Grandma. Then it was tucking into one of her dinners. Well, not so much tucking in as devouring it like a pack of wolves who'd spent three months on the watercress soup diet.
'Dee-licious,' said the six-year-old scraping a plate clean for the first time in his life. 'Can I have some more broccoli?'
I almost choked.
'Broccoli?' I said. 'Are you sure? You don't like it at home.'
'I know,' he said, looking past me and smiling at his grandmother. 'But Grandma's broccoli is much nicer than yours.'
And it wasn't just the food they loved. In the presence of their grandparents, my children were transformed. There was no bickering, no tears, no throwing themselves on the floor in temper over who had the biscuit with the most chocolate on it.
Instead, they were having the time of their lives.
It was strange. Even though they saw their grandparents just three or four times a year, the kids seemed to understand that this was somewhere they belonged. Not for the first time, I wished their grandparents didn't live so far away.
'So do I,' my mother-in-law said to her daughter as we talked about it the evening she'd arrived by train. 'But it was Rebecca who moved away. Not us.'
It was true. In her late teens my wife couldn't wait to get as far away from home as soon as possible. Now, 20 years on, she wonders if she made the right choice. Trouble is, we both feel cut off from our loved ones. And, more importantly, so do our children.
The Grandparents' Association estimates there are more than a million grannies and granddads who are denied access to their grandchildren. But that figure represents only those banned from having contact, usually because of their children's bitter divorce. How many more grandparents and grandchildren are separated simply because they live so far away from each other?
It wasn't like that when I was a child. Both my grandmothers lived close by and we saw one or other of them almost every weekend. They babysat for us, they came on holiday with us and they were as much a part of every Christmas as Santa and his reindeer.
All too soon, the week-long stay came to an end and we were packing the cases again and looking under beds for missing teddies and stray socks. And that's when my wife noticed her nine-year-old daughter, my stepdaughter. She was standing in her grandfather's den, staring at a photograph on the bookcase.
'Who's that, Mum?' she said. 'He looks like someone I know.'
Gazing out of the sepia tint was a young man, no more than 22 or 23. He was wearing an army uniform adorned with a medal ribbon. There was something very familiar about his face and yet the photograph was dated 1917.
'That,' my wife said, 'is your great granddad, my grandfather.'
Her eyes widened.
'I didn't know you had a granddad,' she said.
'He died a long time ago,' my wife said. 'When Grandpa was a little boy.'
'So you didn't get to meet him?' she said.
I shook my head. Child 1 thought for a moment. 'I'm glad I've got all my grandmas and all my granddads,' she said at last. 'I'm lucky to have them, aren't I?'
'Yes love,' my wife said. 'You really are.'
She looked at me to check my reaction. I smiled. I lost my mother last December. My sons barely knew her, and she certainly didn't know them because of the way Alzheimer's had stolen her mind. But it was OK. Life carries on.
Then it was time to say our goodbyes. I loaded up the car with the two suitcases, the three boxes of toys, the blue teddy and the three children.
And we were ready for the five-hour journey home. As I turned the key in the ignition, my wife glanced back at the house. Standing on the doorstep were two figures, doing their best to smile. But for the first time they looked small and frail and old. And, suddenly, I saw my wife's throat tighten and her eyes fill with tears, She rubbed them hard.
'What's the matter, Mum?' Child 1 asked.
'Nothing,' she said.
But it was a lie. She was looking at her mother and father and she was wondering how many more times we would see them. How many more times would they cuddle our children on their knee and tell them stories about the faces in the photographs? How many more times would she find them – grandparent and grandchild - staring in wonder at one another? How many more irreplaceable moments like those would there be?
Twenty, perhaps? Maybe just ten? And then the precious link between old and young, past and future, would be broken forever.
I turned off the ignition and got out of the car.
'Y'know, I don't feel up to the drive today,' I smiled. 'Would it be OK if we stayed another day?'
'Of course,' my wife said, brightening. 'But don't you have things you need to do at home?'
'No,' I said. 'Nothing important.'
What she meant was: nothing as important as this.