Clive Dunn cashed in on his fame in Dad’s Army when his sentimental song Grandad topped the chart in January 1971.

I missed this out when I went through the hits of 1970 but its cloying sentimentality chimes with the festive season – and it has a great story behind it.

It was written by Herbie Flowers, the session musician who played perhaps the two greatest bass intros of all time, Lou Reed’s Walk On The Wild Side and Rock On by David Essex (which I posted yesterday).

Apparently he met Clive Dunn – then playing Corporal Jones in Dad’s Army – at a party, and was challenged to write him a song. Flowers duly bought or borrowed a primer on songwriting for beginners before taking on the task.

This was his first attempt, but he couldn’t come up with a chorus. So in the spirit of a TV quiz show that would not be invented for another 30 years, he decided to phone a friend.

His mate Kenny Pickett, former lead singer of the great Sixties underground band The Creation, duly popped over to help. Ans s soon as Kenny pressed the doorbell, Herbie had that eureka moment.

Which is why Ken gets a songwriting credit on this novelty hit and why, now that you think about it, the two-note melody of “Grandad” sounds like the ding-dong of an electric doorbell.

The finished song is one of very few pop hits to feature a tuba, which is no coincidence either – it was the first instrument Herbie learned to play when he joined the Royal Air Force band during his military service.

Dunn, who was more than a decade away from becoming a grandfather in real life, celebrated his 51st birthday while the song was at No.1 in the charts in January 1971.