There's an interesting paper at http://www.cesg.gov.uk/ellisint.htm which claims that UK spooks invented both RSA and DH in 1973 and 1974 respectively. The summary info is:
This paper by James Ellis was written in 1987. It was commissioned shortly after his retirement to provide a first-hand historical account of the early work by James and others in CESG, discovering the techniques that were later to become known as Public Key Cryptography. Although there would have been some academic interest in the paper back in 1987, it was decided on balance to keep the record internal and accordingly the paper was given a low classification and retained within CESG.
Since 1987 there have been three aspects which have created enormous changes for CESG. First, the growth in the need for secure communications for confidentiality and authentication has vastly increased key management requirements. Second, the increase in processing speed has enabled large arithmetical computations to be practicable. Third, the 1994 RPS gave CESG responsibility for the communications security of the entire UK government market. PKC is now seen as the best if not the only method for allowing wide area many-user secure communications. With this increase in CESG's external visibility there has been a growing desire for greater openness.
During the past 11 years there had been no urgency to publish the paper, but the necessary spark came when Clifford Cocks solved an important problem that had been highlighted at a recent 'RSA' conference. Cliff is presenting this solution in a paper at the IMA Conference on Cryptography and Coding in Cirencester. Since he was one of the main contributors to our early work it was clearly the right opportunity to set the record straight. As the paper was being prepared for publication we heard that James had become very ill. He died before the paper was published. We now publish it as a testament to his imaginative and ground-breaking work.
(The paper was mentioned on a UK crypto list, but I've lost the original reference). Peter.