Perhaps one reason why outright evasion of the Statute of Mortmain never reached uncontrollable proportions was that there existed a good many ways of manipulating it more or less legally into something less restrictive. Some, such as leasehold or enfeoffment to use, enabled the church to dispense altogether with licence procedure. Others, notably the employment of nominees to acquire property with a view to ultimate amortisation, mitigated the inconveniences caused by the legislation. Few of these devices were new. Some had been foreseen by the drafters of the statute, who clearly hoped that its terms would preclude their fraudulent use. In practice, however, it was difficult to draw the line between what was permissible and what was an abuse. Consequently, the church was left with considerable room for manoeuvre. Indeed, so great were the opportunities for modifying the legislative controls that statutory revision of the position was required on several occasions. Thus, there was a far greater risk that the spirit of the 1279 statute would be negated by tactics of nominal legality than by total evasion, which could be pursued and punished.

The first and most radical way in which immunity from the statute could be secured was by claiming exemption from its provisions. A long and bitter dispute arose between the crown and the city of London over this issue. The evidence was thoroughly examined by Miss Chew in her article ‘Mortmain in Medieval London’, upon which the following account largely depends.