In Cambridge, the laboratory as it was then called in the '50s – the Unit, the MRC Unit for the Molecular Structure of Biological Systems. This had been set up by the MRC for Max Perutz some years ago with the idea that crystallography could be of importance for medical research. The Medical Research Council was in fact persuaded by Keilin, who was a very formidable scientist – David Keilin – and of course who was interested in iron proteins. David Keilin discovered the cytochromes in the '20s, and this unit had been set up with the unlikely program of determining the structure of protein molecules by X-ray crystallography, which just seemed totally impossible for things of that size. And of course this was something that Max had worked on and of course there were forerunners, namely Bernal. Now, technically this was very difficult to do. First of all, the data were very hard to record, because the X-ray sources were not powerful enough. And so one of the things that became a part of that group – and that's why they were in the Cavendish Laboratory – was in fact to develop the physical instrumentation to do this. And of course this is where the rotating anode tube had been invented so that a more intense source of X-rays became available and so these crystals could be photographed. Now, one of the problems in doing X-ray crystallography is of course what's called the phase problem. What you measure is the amplitude of the wave and that is the square, but you don't know whether it's minus or plus. And if you have to look at, say, 400 reflections, this means you have two to the four hundred possibilities and so you can't do it in any other way but to determine phase. And for a long time the haemoglobin work that Max was doing just went very slowly, and in fact nearly all the work done up to almost the last time was wrong. In fact, Francis started by working on haemoglobin Pattersons and came to the conclusion it was a waste of time. Jim came to the lab to do X-ray crystallography on tobacco mosaic virus in the lab, because he thought that he could try and tell something about this. So Jim Watson came here. John Kendrew had joined Max Perutz after the war and he had started to work on another protein called myoglobin.