O'Sullivan & Hilliard's The Law of Contract (2018 8 ed). p 115.
5.79 First, there must be a clear and unambiguous promise or representation that the creditor will not insist on his strict legal rights, satisfying an equivalent test of certainty as is required for contractual obligations (see Baird Textiles v Marks & Spencer plc (2002) discussed at paras 3.15–3.18, and BMIC Limited v Chinnakannan Sivasankaran, Siva Limited (2014)). This requirement is not surprising—it is unacceptable to deprive a party of a legal right unless, judged objectively, this was the only plausible interpretation of his words or conduct. More important is the requirement that the promise must relate to existing legal rights, a significant limitation because it means there must be an existing legal relationship between the parties. Promissory estoppel cannot take the place of consideration when a contract is being formed for the first time between the parties, only (as in the Foakes v Beer problem) when existing contractual rights are being varied. Denning J did not emphasise this restriction in High Trees (although, of course, the landlord’s representation there was as to existing legal rights—the right to claim the full rent) but it has been applied ever since. Brennan J regarded this restriction as ‘illogical’ in Walton Stores v Maher (see para 5.94): ‘If a promise by A not to enforce an existing right against B [1.] is to confer an equitable right on B to compel fulfilment of the promise, why should [2.]B be denied the same protection in similar circumstances if the promise is intended to create in B a new legal right against A?’
Please ELI5 the bolded phrases.
Once 'an equitable right' is conferred 'on B', who's compelling the fulfilment? Who's the promisee ?
Why would "B be denied the same protection in similar circumstances if the promise is intended to create in B a new legal right against A"?