“It seems to us that the correct approach would have been to start with the written contractual arrangements and to have enquired whether they truly reflected the intention of the parties. If they did, then the next question was whether on the commencement of their employment, the applicants were employees of (a) or (b). If the conclusion was that, when properly construed, on commencement of their employment the applicants were employed by (b) then the chairman ought to have asked the question:- ‘Did that position change and, if so, how and when?’”