Quick answer

It depends on the wording: a properly made omission is not a breach and gives no automatic claim, so lost profit must be found in the contract mechanism; where the contract allows recovery of direct loss and/or damage the profit can be reached, as in Wraight, whereas the argument that a rate adjustment or fair valuation should itself include lost profit is arguable rather than a settled entitlement

It depends on the wording of the contract. The standard forms provide for work to be varied, including by omission, so a properly made omission is not a breach and there is no automatic claim for lost profit. Recovery then depends on finding wording that reaches the profit. In Wraight Ltd v PH and T Holdings Ltd the words direct loss and/or damage were held to include loss of gross profit, so a contract worded like clause 11(6) of JCT 63 would allow it; JCT 2011 has no equivalent, its clause 4.24.1 applying only where regular progress is materially affected. Under the ICE Editions, clause 52 allows contract rates to be adjusted where the varied work renders them inappropriate, and it can be argued, drawing on Mitsui Construction Co Ltd v Attorney General of Hong Kong, that the adjustment should allow for lost profit. Bonnells Electrical Contractors v London Underground shows lost profit recoverable on a wrongly determined call-out contract for the notice period. Under JCT 2011, clause 5.6.1.2 gives a fair valuation where a substantial omission changes the conditions of the remaining work, and quantity surveyors commonly allow some profit where substantial work is omitted. The distinction matters: the direct-loss wording is the established route to lost profit, whereas the argument that a rate adjustment or a fair valuation must itself include lost profit is not a settled entitlement and turns on the clause and the facts.