I can't really claim to have known my paternal grandfather Max Rabinovitch.

I was not quite five when he died. All I can recall is an old man with a beard and a kippah in a gloomy house in Chapeltown and a tearful tussle with him over a Meccano windmill. Of my grandmother, who died a year before him, my only memory is a terrible tummy ache after eating her latkes. If I were Marcel Proust, I could probably make something of that but, for me, it's not enough. Though my late father did tell me the odd thing, our family history is tallissed in mystery. We might have learnt more from a memoir left by our great-uncle Zelmer but nobody read it and probably nobody ever will because my cousin had it and he's lost it.

What I do know is that Max was an Orthodox Jew but an unorthodox and adventurous man. He arrived by himself from Russia, aged 11, and learnt watchmaking by watching men doing it. Of Jewish car drivers in Leeds, legend has it he was the first and, I hope, the worst - he drove a De Dion-Bouton often too fast and too often without lights. If Chris Huhne had as many endorsements as my grandfather's 1909 annual licence, he'd be banged up in Dartmoor for the duration.

My grandparents married in Leeds in August 1899. My grandmother Rebecca Amalia Rosenberg was a shy, refined rabbi's daughter who had a lot to contend with. Once, when Max couldn't get home from somewhere he bought an aeroplane.

His financial fortunes went up and down. He had a watchmaking business in Leeds. Painted on the outside wall of his shop was the promise: "Any single item at wholesale price" (a deal I emulate by writing this column). He owned a cinema (or maybe more than one) in Sheffield.

He was an unorthodox, adventurous man

When he was flush, he bought, without telling his wife, Potternewton Hall, a vast Georgian Leeds house in extensive grounds. When the building was knocked down in 1935, the best interiors were preserved and one panelled room is now in Samantha Cameron's father's house near York. My grandmother was having none of it. She refused even to go and look at Potternewton Hall. I suspect the word "meshuggah" was mouthed. Max had to sell it at a hefty loss.

On October 1 1934, my father and his brother Joe, both doctors, changed their names to Robson, which seemed a good idea at the time. Some not-too-much-loved cousins were doing the same thing. Perhaps they would have liked to Robsonise themselves, too, but Joe told them a different R name that they took up. Thus they were uncoupled for ever which also seemed to Joe and my father a good idea at the time.

Was anything gained by the name change? Being Jewish still meant Uncle Joe couldn't be a member of the Cumberland tennis club in London. Being Jewish meant that my father wasn't given the medical job he should have had in Yorkshire.

As for me, as a journalist I could never summon up the chutzpah to express opinions on everything from aardvark to Zumba. I could never be David Aaronovitch but I could at least be David Robinovitch.