The former Conservative health secretary was diagnosed with bowel cancer after his wife nagged him into seeing his GP about his back pain. While his prospects would have been better if it had been caught earlier, things could be worse. He is still fairly optimistic about recovering, and he isn’t asking for your sympathy – although it was classy of the shadow health secretary, Jon Ashworth, to offer Labour’s anyway.

What he does seem to want, however, is for his own party to acknowledge that lucky isn’t good enough, either for him or for the millions of over-55s in England and Wales supposed to benefit from a national screening programme to detect and treat bowel cancer early. This was something Lansley himself piloted in office, before finding out the hard way that it hasn’t been delivered as planned.

About half the population did get access to testing, which can pick up and treat the disease in its earliest, highly survivable stage, and Scotland has introduced routine screening for the over-50s. But for the other half, things aren’t so rosy. Crucially, Lansley blames that not just on IT failings and a shortage of endoscopists but, at least in part, on Treasury cuts (since reversed) to a body overseeing NHS workforce development.

When a former Conservative health secretary is diagnosing the NHS’s problems in these terms, it’s no longer possible for his own party to ignore the perennial elephant in the room: money.

There is an emerging consensus across politics now that the health service can’t patch things together for much longer – that neither a bafflingly technocratic reorganisation (Lansley’s own rather dubious contribution to the health service), nor shielding its budget from the austerity cuts imposed on other departments, was enough to solve its problems. Put bluntly, it needs more cash – which is why Jeremy Hunt, Lansley’s successor at the Department of Health, has recently reopened the debate over the funding of long-term care.

But the time for tiptoeing tactfully around the fringes of this argument is over. Everyone needs to stop pretending that Britons can have all the healthcare they want at no extra cost, and to start making the case for tax rises before the service falls even further behind public expectations.

For Lansley’s story also hints at a wider debate about preventive medicine more generally, and what it’s reasonable for all of us to expect. As the healthcare thinktank the King’s Fund has tirelessly pointed out, the biggest pressure on health spending in recent times hasn’t actually been an ageing population but technological leaps and bounds: things becoming possible that a decade or two ago couldn’t even have been imagined, but which it now seems unethical to withhold.

Screening isn’t always the panacea people think. There are careful judgments to be made about the benefits of catching something early versus the risks of over-treatment – pushing people into radical surgery when it’s not yet clear how aggressive their particular case will turn out to be, for example – or of false positive results clogging up NHS clinics with people who aren’t actually ill. There are ethical considerations with some diseases, too, about telling people they’re in the early stages of something incurable.

But once a test exists people, not unreasonably, want to have it; and once they’re promised it – as people were in the case of bowel cancer – they rightly expect politicians to deliver on those promises. Screening and treating early, before cancer gets a chance to spread, has the capacity to save not just thousands of lives but millions of pounds, which could in turn be used to save more lives. But it’s downright dishonest to pretend all of that can be done for little or no upfront cost in a service that’s already struggling to cope with acute cases landing on its doorstep, never mind people who don’t actually realise yet that they are sick. History may not make much of his achievements in the job, but Lansley has done the NHS and those who use it a belated favour by being honest about what now ails it. Let’s hope that diagnosis hasn’t come too late.

• Gaby Hinsliff is a Guardian columnist