Alan v El Nasr [1972] 2 WLR 800 

By contract, the sellers agreed to sell 250 tons of coffee beans at 262 Kenyan shillings per cwt to El Nasr payable on credit. At the time of the contract the value of Kenyan shillings and pound sterling were of equal value. Whilst the contract stipulated the price payable in Kenyan shillings, the credit account referred payment in pound sterling. There were a number of other discrepancies between the credit agreement and contract such as date of shipping and the quantity to be shipped. These other discrepancies were rectified in a revised agreement however, the new agreement still referred to payment in pound sterling. The sellers accepted the first instalment of 57,000 in pound sterling without objection, however, the value of the pound dropped quite dramatically resulting in a loss of 165,530.45 shillings. The sellers then sought to revert to Kenyan shillings and demanded the further payment. The buyers raised promissory estoppel in their defence in that in accepting the instalment in pound sterling and redrafting the credit agreement without changing the currency there was an implied promise that they would not revert to Kenyan Shillings. The sellers argued that the buyers had not acted to their detriment in reliance of this promise as they had gained a benefit.

Held:

Detrimental reliance is not a requirement of promissory estoppel. It only needs to be established that the promisor has changed their position.

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