When Sir Anthony Blunt's misdeeds were exposed to public gaze by revelations that he was the so-called fourth man in the notorious group who had spied for Russia, an important area of the criminal justice process was partially uncovered as a result. The Prime Minister confirmed in a House of Commons Written Answer that Mr. Blunt (as he later became) had been granted immunity from prosecution as long ago as 1964 by the Attorney-General, Sir John Hobson. No attempt was made to suggest that this was a routine occurrence, but in the ensuing debate, the Prime Minister asserted that “it is not unusual for the Attorney-General to be asked to authorise immunity from prosecution in return for co-operation in pursuit of inquiries. It happens from time to time in the course of criminal investigations.”

Over a hundred years have passed since the Judicature Acts rationalised the law relating to the assignment of choses in action and made it easier for an assignee to enforce his rights. Nowadays the assignability of contractual rights is important in both business and consumer affairs, since credit is commonly obtained on the security of insurance policies, hire-purchase contracts, and traders' and builders' book debts. Yet although the Judicature Acts facilitated these developments they did not deal with the possibility that a contract may expressly prohibit or restrict the assignment of rights arising under it. Many standard form contracts now incorporate a clause to this effect. Where an assignment is made in contravention of such a clause, does the transaction have no effect? If this is the case, non-assignment clauses would seem to pose a serious threat to current lending practices. The courts have had to consider this question in a number of cases and the result is a confusing array of Conflicting views.