A sold coffee to B, charging in “shs” which could have referred to Kenyan shillings or British sterling. Payment was later accepted in sterling, until it became devalued against the Kenyan pound. CA held that looking at the circumstances the original price was charged in Kenyan shillings. However, Denning LJ held that the sellers had waived their right to be paid in that currency having accepted payment in sterling, while the other two CA judges held that the seller had accepted a variation in the terms of the agreement.
Lord Denning: Where one party induces another to act a certain way by promising not to assert strict legal rights, one cannot immediately renege on that promise, even if the promisee acted in a different way to how one expected, upon learning that the promisor would not assert strict legal rights.
Neither the approach of “modification of the contract” makes sense since there is no consideration coming from the promisee (in fact it has been to the seller’s harm), nor the approach of estoppel/waiver (since the circumstances were clearly too unclear given the requirements set out in Woodhouse).