I'm a big supporter of the NHS in theory, and I'm hopeful that the rancorous glee with which this particular GP refused to address anything that ailed me was atypical. But the NHS preventive services in relation to bowel cancer — the second biggest cancer killer in Britain — are woeful. The service has at least brought in sigmoidoscopies, a less thorough examination that's certainly better than nothing, but not until age 55, and only as a one-off. Otherwise men and women between the ages of 60 and 75 are posted stool kits whose samples are tested for blood — thus detecting not precancerous polyps but cancer, already advancing. It can't just be a coincidence that the UK has rubbish colon screening and some of the highest mortality rates for bowel cancer in the Western world.

Surely this is penny-wise policymaking. Surgery and chemo for bowel cancer cost massively more than a colonoscopy, which even in the private sector can be had — that's right — for £1,630.

I am one of the many people on whom any functional health service depends: I part with large sums of money for practically nothing in return. For most of the paltry services I require I'm forced to go private. It seems the height of ingratitude to complain about being in good health. Nevertheless, I have plenty of company here, and my cohort makes the NHS possible: we pay for it, and hardly use it.

I might advisedly keep my resentment in check, since with the untimely turning of a large lorry in the vicinity of my bicycle this situation could change on a dime. I realise as well that the NHS is sitting on a demographic timebomb, and cannot pay for everything; I myself have lobbied for elective services like gender reassignment and even fertility treatments to be curtailed, the better to cover core healthcare. Yet on this one point both public and private health insurance in the UK are making a mistake: especially if polyps run in my family, it's worth your fiscal while to ram a camera up my butt.

Besides, the prep for a colonoscopy is so disagreeable, how many Britons would submit to it even for free? Surely anyone willing to subject themselves to such humiliation for purely preventative purposes should be sent home with an appreciative plaque for civic-mindedness and a box of chocolates.  Downing two litres of a nauseous liquid — most of it salt, poorly disguised with aspartame — in order to . . .  well, perhaps there's a place for decorum.

I was delighted the internist found a polyp, since that means the next one's on the NHS, at which time I'm hopeful I get the same GP, with whom I can be vengefully gleeful myself. For that matter, to get back at that smug doc, I'm tempted to make a few lifestyle changes. I could start hoovering up all the chips, crisps, biscuits and cream buns on which I've hitherto foolishly stinted. I could reduce my daily exercise to a sluggish lumber across the street for another packet of fags. In the fullness of time, I figure I could wheeze into that clinic and finally get my money's worth.