"The following paragraphs summarise your main conditions of service as they will apply from the29th May 1990 ... Details of conditions of service applicable to Civil Servants are to be found in the Staff Code and the Civil Service Pay and Conditions of Service Code ... You will work 24 hours a week ... These Revised Terms and Conditions of Service are offered as a result of your application. They may be terminated by you, or by management, provided that at least one month's notice is given. You may ask Management to consult your Trade Union if you wish the arrangement to continue. In the event of your being unable to continue with the arrangements, or wishing to revert to full-time work, the continuation of the arrangement will be subject to renegotiation and, if appropriate, you will be offered a full-time post as soon as possible. When you resume full-time work the suspended terms of appointment will be reinstated."
"When an individual gives notice he or she wishes to end a part-time arrangement, although it cannot be guaranteed that a full-time post will be readily available, every possibility, including that of a voluntary transfer, will be explored to ensure as quick a posting as possible."
"The Tribunal heard a considerable amount of evidence as to what transpired thereafter but, in essence, her request of return to full-time working was refused by the Divisional Manager of the Contributions Agency [Mr Rushton] on the basis that this would have rendered the number of full-time employee[s] over complement and [would have] been contrary to the financial restrictions anticipated under the Public Expenditure Survey Settlement for the following year.
"Dear Marian,
"The Tribunal is of the unanimous view that something that has been happening over a number of years and may indeed have become perceived as the norm does not thereby become a term of the contract."
"The relations between landlord and tenant have been so long regulated upon the supposition that all customary obligations, not altered by the contract, are to remain in force, that it is too late to pursue a contrary course; and it would be productive of much inconvenience if this practice were now to be disturbed."
"Usage" is apt to be used confusingly in the authorities, in two senses, (1) a practice, and (2) a practice which the Court will recognise. "Usage" as a practice which the Court will recognise is a mixed question of fact and law. For the practice to amount to such a recognised usage, it must be certain, in the sense that the practice is clearly established; it must be notorious, in the sense that it is so well-known, in the market in which it is alleged to exist, that those who conduct a business in that market contract with the usage as an implied term; and it must be reasonable. The burden lies on those alleging "usage" to establish it ... - ... Practice is not a matter of opinion, of even the most highly qualified expert, as to what is desirable that the practice should be ... Arrangements or compromises to the same effect as the alleged "usage" do not establish "usage"; they contradict it. They may be the precursors of "usage"; but "usage" presupposes that arrangements and compromises are no longer required. It is, in my view, clearly not necessary that a practice should be challenged and enforced before it can become a "usage", as, otherwise, a practice so obviously universally accepted and acted upon as not to be challenged could never be a usage. However, enforcement would be valuable and might be conclusive in establishing usage. ... A party to a contract is bound by "usages" applicable to it as certain, notorious and reasonable, although not known to him. If the practice, though certain and notorious, is unreasonable, it of course follows that it cannot constitute a "usage" which the Court will enforce as a "usage". Nevertheless if a party knows of such a practice and agrees to it, then though unreasonable, he is bound by it (Perry -v- Barnett, Blackburn -v- Mason)."
"Thus, in the absence of evidence of a contrary intention, a Court may import into a contract any local custom or usage which is notorious, certain, legal and reasonable and, provided that it can be shown that the custom or usage normally governs the particular type of contract in question, it will be regarded as part of that contract in precisely the same manner as if it had been expressly agreed between the parties"
"Their Lordships, however, are unable to treat these matters as establishing contractual liability by the railway company to the Appellant. The fact that the railway company applied the agreement to the Appellant, is equally consistent with the view that it did so, not because it was bound contractually to apply it to him, but because as a matter of policy it deemed it expedient to apply to all.