Philip Morris International – which makes Marlboro and several other leading brands – has vowed to phase out cigarettes and move into smoke-free products instead. And the complex of laboratories is a signal of intent. It’s spent £3.5bn on science and technology so far, clocking up more than 3,000 patents, with another 5,000 pending.

The current focus is on IQOS, an electric device that heats, rather than burns tobacco. The cooler temperature lowers levels of 15 noxious chemicals found in cigarette smoke by 95%, according to the company’s research. Sky News was given unprecedented access, allowed to see banks of machines that “smoke”, and a laboratory where scientists monitor the impact of chemicals on the tiny hairs inside the lungs and airways.

That doesn’t mean it reduces the risk of smoking-related diseases. Those studies haven’t been done, though blood tests suggest there is a less damaging impact on the body. Nor have there been head-to-head comparisons with vaping. The aerosol from heating nicotine liquid has even lower levels of toxic compounds. And while medical authorities endorse vaping as an alternative to smoking, they are so far sniffy about heated tobacco.