The issue here is whether part payment of a debt extinguishes the debt. According to Pinnel's case (1602), part payment of a debt does not usually satisfy the entire debt. This was also confirmed in Foakes v Beer (1884). However, there are certain exceptions to this rule, such as, if early part payment was requested by the lender. In that circumstance, the early part payment could be satisfaction for the entire debt. Since Ken requested the repayment of the debt from Barry before the debt was due, this would constitute early part payment of the debt. Ken also agreed to accept the £2000 as full satisfaction of the debt. Therefore, according to the exceptions laid out by Pinnel's case, Barry's payment of £2000 would extinguish the debt. The issue here is whether silence can form a legally enforceable contract. To form a contract there must be an offer, acceptance, consideration and intention. In a bilateral contract, acceptance is valid when it is communicated to the offeror. Silence does not constitute valid acceptance, as found in Felthouse v Bindley (1862). In this case, there is an offer from Ken to John. However, John did not respond to communicate to Ken that he accepts the offer and so no valid acceptance has occurred. This means that there is no legally enforceable contract. The issue here is whether promissory estoppel can apply and whether a variation in contract can be reverted to the original contract. For promissory estoppel to apply, there are six requirements to be fulfilled, according to the High Trees case [1947]. There must be an existing legal relationship, it must be used as a shield not a sword, it must be clearly represented, there must be reliance on the contract, it must be inequitable to go back on the promise (D & C Builders v Rees [1966]) and the doctrine is only suspensory. If these requirements are fulfilled, then the offeror can be estopped from going back on the promise to the offeree. Furthermore, the doctrine of promissory estoppel is only suspensory which means that the offeror can revert to the original terms of the contract whenever they wish, if notice is given. There is an existing legal relationship between Ken and his landlord since they have a contract that Ken must pay rent each month in order to live in the flat. The doctrine would be used as a shield and not a sword since Ken would be using it as a defence for having to pay the difference in rent amount. There was clear representation and a reliance on the promise since Ken had been paying the lower rent for a number of months. Finally, it would be unfair to go back on the promise because Ken and the landlord had both agreed to the lower rent amount, supported by Builders v Rees. Since all the requirements are fulfilled, the landlord would be estopped from claiming the difference in rent for the previous months, in line with the