The starting point is that the contract will be enforced in accordance with the version signed by the parties, ie with the errors still contained within it. However, the precise effect of the errata will vary on a clause-by-clause basis. If the error in the original version leads to an ambiguity or inconsistency then, pursuant to clause 1.5, the Engineer (or, in the case of the Silver Book, the Employer) can issue a clarification or instruction to address the ambiguity or inconsistency on the basis of the errata. In the alternative, depending on the nature of the error which is corrected by the errata, a claim could be made for rectification by construction. The locus classicus for the principle of rectification by construction can be found in East v Pantiles and, in particular, the judgment of Lord Justice Brightman where he said as follows: ‘It is clear on the authorities that a mistake in a written instrument can,