A contractor who has loaded a tender BoQ rate in the expectation of a windfall will be interested to learn that recent guidance from the Hong Kong Court of Appeal supports the engineer’s request for evidence of the original tender build up and, among other things, will disallow all loading if substantial differences in actual quantities would make it reasonable to do so under the contract. This article explores that new guidance which finds contract rates to be neither immutable nor sacrosanct in such circumstances.