Hola again. It's the end of our fortnight in Spain with our friends Jake and Rafia and their two small children, and I think we're all relieved to be going home.

Sharing a villa with another family, even a family you know and love, can be trying and I think we have all exposed our less agreeable sides. In fact, if we'd been under the public scrutiny like the Big Brother contestants, the only person not to have been voted out by now would be Jake and Rafia's delightful four-month-old daughter.

Our toddler and their toddler have each developed the other's bad habits so that now neither of them eats nor sleeps. The adults have had disputes over joint expenditure and too much sangria has led to some emotional outbursts.

Still, it's not been a complete disaster. Some important friendship bonding has taken place, too, especially between my husband and Jake on the sandcastle building front.

I'd always laughed at dads who pretended their mammoth sandy fortresses on the water's edge were created for their child's pleasure. And now I have laughed some more ever since the toddlers made it plain that sightseeing and sitting in restaurants were their least favourite activities. We've had some busy afternoons on the beach. To begin with, the two dads went in for modest, one-bucket constructions, which delighted the kids, By last Thursday they had gone into partnership and were building grand fortresses on a sort of McAlpine scale. It started to get out of hand when they invested in some heavy duty plastic shovels and the children didn't get a look in.

When Jake's son picked up one of the new digging implements the dads joined forces in trying to persuade him to swap it for a manky old piece of driftwood.

Other sunbathers found the scene quite curious, too. A group of Germans came over to admire the three 3ft by 6ft hole Jake and my husband had dug themselves into.

When the thunder clouds had gathered and the raindrops forced most people off the beach, the two dads kept on shovelling. By then I had retreated to a bar with two shivering, hungry, bored toddlers who had given up hope of being able to play with their buckets and spades again.

It wasn't until nightfall, with the beach deserted, that the two dad's decided their work was complete. "It's the best fort on the beach," said my husband, doubled up in agony.

Actually it was the only fort on the beach. Building enormous sandcastles must be peculiar to British dads. Foreign dads realise that the effort is pointless since the sea destroys your work the minute your back is turned. British dads obviously have a childish naivety that would be endearing if it didn't adversely affect their relationship with their own kids.

Sorry, I'm being a little harsh on my husband and Jake. The children didn't mind that much and hopefully will have learned something about the importance of team building. Jake, who knows about such things, described the process as "forming, storming, norming, performing".

You get together, you argue, you draw up the rules, you achieve your goals.

It's always good to end a holiday feeling as if you've learned something.