The majority judgments of the Court of Appeal in Henry Boot Construction Ltd v. Alstom Combined Cycles Ltd 1 are valuable (but, it will be submitted, qualified) authority on the interpretation (subject to an understandably vigorous but, it will be submitted, similarly qualified dissent by Ward LJ) on the traditional century-long formula used for valuing variations used not only in earlier RIBA/JCT standard forms but also adopted since 1973 by clause 52 of the domestic ICE Conditions in England (with which Boot was directly concerned), and also overseas in the many FIDIC-related engineering contracts and JCT-related Commonwealth building contracts. That formula, as readers will know, usually takes a sequential form (which on close scrutiny varies slightly in different standard forms and can leave much for interpretation). In the Boot case, variations of “similar character or similar conditions” (i.e. compared to work already priced in the Bills or a Schedule of Rates) are to be valued “at such rates or prices [i.e. in the Bills or Schedule] as may be applicable”. Secondly, if the “character or conditions” of the varied work are not “similar”, the rates and prices in the Bills “shall be used as the basis for valuation so far as may be reasonable …”. Thirdly (the wording continues without any break) “…failing which…” (whatever this may mean in context, but presumably, on the wording, in those “dissimilar” cases where to use a rate or price as a basis for valuation would not be reasonable, as well as where there are no “applicable” rates or prices at all) there is to be a “fair valuation”. (To make sense of the clause 52 wording, “similar” needs to be read as “identical” or “the same”).