The employer in Cartwright v Tetrad Ltd was experiencing financial difficulties and, in order to meet the requirements of its bankers, imposed a 5% pay cut on the workforce without their express consent.  The first reduced pay packet was issued on 10 May but there was no formal objection from union or employees until October. The Tribunal rejected the claimants' claims of unlawful deductions and the EAT upheld this.

In a very short judgment, the EAT agreed that there was an implied variation by consent in the absence of objection by the union or employees for several months.  On the facts, the Tribunal was entitled to conclude that, by continuing to work without protest until 23 October, the claimants had accepted the change in their terms and conditions as to pay.

Case law makes it clear that where the employees' decision to continue working can only be referable to their having accepted the new terms – typically where there are changes to pay or job duties – then if they want to reject the change they must either refuse to implement it or make it plain that they are working under protest. That will not be the position, however, if the variation does not have an immediate practical effect and so does not require a response from the employees.  The classic example often quoted (from a 1996 case, Aparau v Iceland Frozen Foods) is the unilateral imposition of a mobility clause. 

Making unilateral changes to terms and conditions tends of course to be a risky strategy, not least because of the danger of employees resigning and bringing constructive dismissal claims.