Sir Isaac Newton once declared that his momentous discoveries were only made thanks to having 'stood on the shoulders of giants'. The same might also be said of the scientists James Watson and Francis Crick. Their discovery of the structure of DNA was, without doubt, one of the biggest scientific landmarks in history and, thanks largely to the success of Watson's best-selling memoir 'The Double Helix', there might seem to be little new to say about this story. But much remains to be said about the particular 'giants' on whose shoulders Watson and Crick stood. Of these, the crystallographer Ros