In 1937, High Trees House Ltd leased a block of flats in Clapham, London, for a rate £2500/year from Central London Property Trust Ltd. Due to the conditions during the beginning of World War II occupancy rates were drastically lower than normal. In January 1940, to ameliorate the situation the parties made an agreement in writing to reduce rent by half. However, neither party stipulated the period for which this reduced rental was to apply. Over the next five years, High Trees paid the reduced rate while the flats began to fill, and by 1945, the flats were back at full occupancy. Central London sued for payment of the full rental costs from June 1945 onwards (i.e. for last two quarters of 1945). Judgment
Based on previous judgments such as Hughes v Metropolitan Railway Co, Denning J held that the full rent was payable from the time that the flats became fully occupied in mid-1945. However, he continued in an obiter statement that if Central London had tried to claim for the full rent from 1940 onwards, they would not have been able to. This was reasoned on the basis that if a party leads another party to believe that he will not enforce his strict legal rights, then the Courts will prevent him from doing so at a later stage. This obiter remark was not actually a binding precedent, yet it essentially created the doctrine of promissory estoppel.