Gran At Large: When your journey goes off the rails

Then the train gave one of those unexplained jolts. The bag on our table fell sideways; I reached to catch it - too late: out of its open mouth tumbled a large brightly-coloured plastic phone. It crashed to the floor, landing upside down, smack on the central red button, the one you push to set it playing a tune.

Into the business-like hum of the compartment came a new sound: 'Old Macdonald had a farm' played with relentless jollity, very loudly. Twice through. Without stopping.

Once it had started there was no way of stopping it. I did try picking up the phone and stuffing it hastily back in the bag, but you could still hear it only too clearly.

The damage was done. Dozens of earnest business conversations came to a sudden halt, dozens of trains of thought were abruptly derailed. The lady in the opposite seat - power-suited, working at her laptop - gave an indulgent smile and said she had children herself so she quite understood. But I did have a distinct sense of gritted teeth.

It wasn't really our fault. We had to make the journey at very short notice, my ten-month-old grandson and I.

It was the week he and his parents were due to move into their new flat, but the building work was way behind schedule and nothing was ready - no doors to the rooms, no flooring except concrete, neither heating nor hot water. Yet they had to move out of their old flat, as the landlord wanted to move back.

So there was nothing for it - I had to take Jonah home with me to County Durham for however long it took to make the flat just about safe. The only two available seats were in the coach mostly used by business people.

Babies and toddlers are allowed to travel free, so long as they don't actually occupy a seat. But it's hard enough travelling on your own with a toddler without having to keep the child on your knee for the whole three hours, which is why I wanted two seats and hang the expense.

That was the first time I made the journey in the company of my grandson, but certainly not the last. When you live 300 miles apart then long journeys are inevitable from time to time.

Fortunately, none of them has been quite as exhausting as that first one. For a start, I've never since had to do it alone. Also, you can be sure that every journey since then has been planned with military precision. And musical telephones have not been a part of that plan.

Nowadays, we buy a few small things before we set out - a toy car, one or two picture books - and slip them into his 'Bob the Builder' backpack, along with a selection of crayons and a drawing pad. Then, once he's on the train, as soon as he shows the first sign of losing interest in what he can see out of the window, he can dip into the bag and discover each new item by turn, examine it, play with it.

The idea is that the new toys or books will keep him occupied for a good chunk of the journey time. In practice, he'll have been through the lot of them when there are still a couple of hours to go.

That leaves two other entertainment options. First, there's walking. When we made that first journey he wasn't walking. He was a champion crawler, but train floors are not ideal crawling ground. Now, when he needs a change of scene he can be taken for a walk the length of the train, with plenty to see on the way.

Then, there's food. We'll have brought a few of his favourites with us, but you can be sure what he really wants is a bit of your GNER sandwich (no accounting for taste). Or most of it; or even all of it.

But no matter how carefully you plan, it's never going to be easy. And train delays or faulty air conditioning are not just inconvenient if you're travelling with a toddler, they can turn the journey into a nightmare.

Then there'll come a moment like that one, 20 minutes out of King's Cross on the way back to London after Easter, when Jonah stood on the seat and shouted: 'I want to get out of here! I want to get out of here!'

Oh, don't I know that feeling!