ONCE again, the phone rings.

"Hi there!" a hearty, youthful male voice says. "I just wanted to interest you in something that's happening on March 20!"

I resist the temptation to hang up. No-one, surely, has the right to sound so cheery or to use so many exclamation marks in a spoken sentence.

"Have you heard about International Day of Happiness?" asks the caller, whose name I fail to catch. "Huge annual UN initiative. This year it's asking people to focus on their connections with others. You've written about a happiness conference before, so I thought I'd get in touch."

"Okay," I say, non-committally.

"Anyway, to raise awareness of the day, the UN's compiling the world's happiest playlist - the songs that make people happy. Can I just ask, what sort of songs do you listen to cheer yourself up?"

I gaze into the middle distance. "Apart from The Smiths, Radiohead and the odd bit of death metal, you mean?"

"I guess we're looking for something slightly more upbeat. Like that great song Happy, by Pharrell Williams. Something along these lines. So, what are your favourite songs, the ones you put on when you really need cheering up, the ones that always make you optimistic?"

I stare out of the window, giving the matter some thought. Eventually, I give him a playlist that includes Hank Williams' I'm So Lonesome I Could Cry, Billie Holliday's Strange Fruit, and I Wish It Would Rain, by the Temptations. Oh, and my favourite song ever - Hurt, by the late Johnny Cash.

Silence from the other end. "These are the songs that cheer you up?"

"You don't know the half of it," I say.

He sighs, then tries a fresh tack. "What sort of things make you happy?" he asks, enthusiastically. "I'm interested."

I gaze out of the window again for inspiration. "Cream-coloured ponies," I begin.

"Hold on," he says, "I'm writing this down. This is good, this is good. At last we're getting somewhere. Cream-coloured ponies ..."

"Crisp apple strudels."

"Crisp apple strudels ..." I hear the sound of scribbling.

"Doorbells and sleigh bells."

"Doorbells and sleigh bells..." He pauses. "This is beginning to sound familiar," he says, finally. The penny drops. "You're just quoting that song from The Sound of Music, aren't you?" he says, his voice betraying a twinge of irritation.

He rings off, but not before asking me to plug the website, www.dayofhappiness.net. He insists it's the least I can do.

Happy to oblige.