After my first wartime experiences with the Medical Research Council, I continued working for them for 20 years in all. And it was a kind of long, extended apprenticeship in certain ways because it covered many branches of science. I worked in the physiology division of the National Institute, in the Virology and Bacteriology division, in Experimental Biology and I finished up in the Biochemistry division before I left in 1961.

And during that time, I encountered a wide range of problems, and science in those days, that was the 1940s to 1960s, was very different from now in other ways than safety regulations. For example, scientists were expected to invent and make their own apparatus. There was very little money available for the purchase of equipment, but ample facilities were provided at the National Institute to make your equipment. You could either do it yourself or ask the chaps in the workshops to build it for you. And there was also a very up-to-date electronics workshop that would help you with building amplifiers and things like that.

Now, this had a rather interesting consequence. Because we couldn't just buy things off the peg like they expect to do now, we had to invent, and this meant that automatically our equipment was 5 years in advance of anything on the market because that's how long it takes a manufacturer to put a new idea into the market place through R&D [research and development] and production and so on. So, we were ahead of everybody and one of the important things that was invented at the National Institute at Mill Hill was the science of gas chromatography. This was invented by Archer Martin and his colleague, Tony James. It was an invention so important that it got Archer Martin a Nobel Prize, quite deservedly so too.

And it probably has done more worldwide to advance industry than almost any invention during those periods. Now, the gas chromatographs that they made was a splendid instrument and answered a lot of problems but it was rather insensitive, it could only handle relatively large quantities of samples. When I say large I'm talking about a milligram, but in biochemistry and biology you occasionally have situations like if you want to know what's inside a single cell. You're dealing not with milligrams, nor even micrograms, but picograms or nanograms and those are very small quantities indeed.

So, I got involved with him in the invention of much more sensitive detection devices, and the first successful one I made was a thing called an argon detector that used a gas argon, it's a rare gas that's present in about 1% in the atmosphere, but it's got intriguing electronic properties that make it very suitable for the detection of traces of compounds in the stream of gas coming from the chromatograph column.

Now, in the course of this invention I accidentally stumbled on another detection device, which I'll call the electron capture detector, or ECD as most people call it, and this device was much more than just a sensitive method of measuring small quantities of chemicals. It was rather special, it was the most sensitive device, chemical analytical device in existence. It could measure down to 100,000 molecules. Which is a tiny, tiny amount of material, so small for example that if somebody spilt a litre bottle of a chemical it could measure in Japan and let it evaporate into air, we could pick it up here in Devon two weeks later, and you could pick it up anywhere in the world with this device in two years, the time it takes to mix with the atmosphere. So, it was, it was and still is one of the most exceedingly sensitive things ever. But it was much more remarkable than that, it was also uniquely sensitive to nasty things. It detected all the pesticides, all the carcinogens, all of those sorts of chemicals, but nothing else. And using it, scientists in other parts of the world were able to demonstrate that the pesticides like DDT [dichlorodiphenyltrichloroethane] and so on were spread throughout the whole global environment. You could find them in the fatted penguins in Antarctica or in the milk of nursing mothers in Finland. And this was the base data that gave Rachel Carson the information that enabled her to write her famous book, Silent Spring, which I think everyone agrees was the start of the green movement and the environmental awareness that we now have. It was the device, the electron capture detector, that made us realise that pollution was global, not just local in scale. But it didn't stop there, because several years later it demonstrated that the chlorofluorocarbons were present in the atmosphere, because they were yet another thing that it could detect, and were building up in concentration and this led to the recognition that the ozone layer was in danger, which about… which I think everybody knows.