"This statement contains particulars of certain of the terms of your employment. Other terms and conditions are contained in the Employee Handbook and in any applicable Trade Union Agreement."
"16. Following completion of your overseas leave entitlement, you will, subject to satisfactory service re-commence employment on your normal U.K duties established prior to the commencement of this agreement at your normally established U.K. salary .....
"We are pleased to confirm your transfer from Overseas Operations to U.K. Chains Department with effect from1st January 1985 as Assistant Station Engineer at a commencing salary of£9960.36 per annum. We confirm continuity of service and conditions of employment will remain the same expect where advised by the Head of U.K. Chains Department."
"So the issue under paragraph 9(2) must be answered by reference to the relevant terms of the contract of employment, express or implied. In the ordinary way ..... one may not look at what the parties did under the contract for the purpose of construing its terms. There would seem, however, to be an exception to the strictness of that doctrine where there must be a relevant term, but what that term is cannot be ascertained otherwise than by looking at what the parties did ..... But such evidence, if admissible in a particular case, must be treated with special care."
"In such a case as the present it appears to us that the correct approach is to look at the terms of the contract, express and implied (with reference, it may be, to what has happened under the contract, for the limited purpose which we have expressed above) in order to ascertain where, looking at the whole period contemplated by the contract, the employee's base is to be. It is, in the absence of special factors leading to a contrary conclusion, the country where his base is to be which is likely to be the place where he is to be treated as ordinarily working under his contract of employment. Where his base, under contract, is to be will depend on the examination of all relevant contractual terms. These will be likely to include any such terms as expressly define his headquarters, or which indicate where the travels involved in his employment begin and end; where his private residence-his home-is, or is expected to be; where, and perhaps in what currency, he is to be paid; whether he is to be subject to pay national insurance contributions in Great Britain. These are merely examples of factors which, among many others that may be found to exist in individual cases, may be relevant in deciding where the employee's base is for the purpose of his work, looking to the whole normal, anticipated, duration of the employment."