Diary of a single father
Seth has spent the day on location with the BBC, filming a sequence for a long-running soap opera. It goes something like this. First a helicopter descends upon the Royal National Orthopaedic Hospital in Stanmore. Then an actor, strapped to a stretcher, is rushed to the Spinal Injuries Unit. "How serious is it, doctor?" he asks. "Will I ever walk again?" The medic smiles. Good news, surely.

"Do you mind being back here?" I ask Seth, when I turn up in the evening to collect him. My son considers the question. "No," he replies. Why should he? How could anyone think unquiet thoughts on such a summer's night? The cerulean sky is simply too benign. Even so, I cannot help but recall a scene that occurred here two summers ago.

It happened in Ward 8. Fran - my wife, his mother, our holy ghost - had been resident since the previous February, when she had suffered a six-hour operation to remove an osteosarcoma from her sacrum. By June, despite a false spring, she was in desperate trouble. The consultant, Mr Pistol, asked to see me in camera. "I'm afraid I didn't tell Mrs Sinclair the truth," he said, holding an x-ray up to the light box. "Look at this erosion. There is no doubt that the cancer has returned." "Does this alter the prognosis?" I asked. "Is a cure still possible?" Mr Pistol looked uncomfortable. No wonder so many people prefer soap opera to real life.

Seth's job is to assist the floor assistants, best described as personalities made flesh. Already he looks the part, sporting white T-shirt, Levi 501s (mine, actually), and a talkback (a headset with a tiny mike attached). Crew members approach and whisper: "The kid's terrific, like a duck to water." In reality Seth is still a schoolboy, and this two-week interlude merely work experience, but he has seen the future and he loves it. "I only hope his dreams come true," says my father, much moved by his grandson's enthusiasm. "Tell me," he says, "how did you manage to get him into the BBC?" "I slept with the right people," I reply. "People?" he says. "Men, women," I say, "whatever it took."

Seth is following a family tradition. As a young man my father frequented the studios at Elstree, pleading for a job; alas, he never got past the gates. As for myself, between visions of being the new Toulouse-Lautrec and a born-again Franz Kafka, I considered becoming England's Ingmar Bergman. A visit to a theatrical agent put paid to that delusion. "Are you ruthless?" he enquired. "Are you a bully? Can you dominate a room?" Even then, I found it hard enough to be myself, let alone pretend to be someone I was not. Instead I elected to become a hermit and write books. My father, however, was more persistent.

"Have you heard of Paul Robeson?" he asks Seth. "Of course," his grandson replies indignantly. "Good," says my father. "Not only was he a superb actor, singer, and athlete, but he was also a political thinker, a man of the left. In short, an authentic hero. Who is his equal today? Perhaps only Nelson Mandela. It's still difficult to believe that I actually trod the same stage as him." "You're joking," gasps Seth, who has a proper respect for the giants of yore. "It's the gospel truth," says my father, "it was, in some ways, the greatest night of my life. You must understand that in the Thirties I was something of a political firebrand, eager to fight fascism wherever it reared its ugly head. I didn't get to Spain, but I was at Cable Street when we stopped Mosley's blackshirts from marching. At that time a new theatre opened in St Pancras, called the Unity. It was a co-operative venture, dedicated to the cause. I joined as a stagehand, my main task being to lay out the costumes for the performers. It may not sound much, but it was quite important. At the beginning of 1938 we learned that our next production was to be an American play about working-class solidarity, Ben Bengal's Plant in the Sun. The sensational news was that Paul Robeson had agreed to play the lead, a character called Peewee. On opening night, I was summoned by Herbert Marshall, the director. He asked me if I was prepared to take a small part, which required me to learn two lines. The Goldington Street theatre was full of posh critics, more accustomed to West End extravaganzas. My heart pounded, my ears buzzed. 'You bet,' I said. The reviews were great, though none, I recall, mentioned me." "Wow," says Seth.

Thanks to my son, I am allowed through the BBC's gates at Elstree. Unlike the pubescent girls who have gathered in their dozens. "What are they doing here?" I ask the gatekeeper. He offers four words by way of explanation. "Top of the Pops". Seth has been to a rehearsal, with his new friends the floor assistants. "Paul Weller was great," he informs me, "but the others were disgusting." As we drive out of the compound, and enter the gauntlet of jail bait, the precocious sirens all lean forward. Several wave their arms and scream. "Who are they yelling at?" asks Seth. "Not me," I reply, as I turn left on to Clarendon Road. With the screams still echoing, father and son drive off into the sunset

Starting next week: Alex Kershaw's diary. Clive Sinclair returns in the autumn