The British government missed out on the billions generated by the sales of public key cryptography, because it didn't realise an algorithm could be patented.
The technology that led to the formation of RSA Data Securities, now thought to be worth around $2.5 billion, was independently developed some years earlier by British researchers working for GCHQ. But because the work had been carried out by the secret services, it was kept under wraps for years.
When the MIT researchers Ron Rivest, Adi Shamir and Leonard Adleman - who went on to found RSA Data Securities - developed the same kind of technology in 1977, GCHQ maintained its silence.
The organisation now concedes that had it had any idea how much money the algorithm would be worth, it probably would have acted differently.
The full story is told in this Sunday's edition of "The Science of Secrecy", the Channel Four serialisation of Simon Singh's "The Code Book" at 6:45pm. ®
In keeping with the cryptographic mood of the moment, El Reg is running a competition to win a copy of The Code Book. All you have to do is decipher the true meaning of the passage we've posted, and no, we didn't just type stuff in at random.
Go here for the contest details.