Commonwealth of Australia (C) sank Verwayen's (V) boat and C said that it would not, as a policy, take advantage of statute of limitations and therefore it would have to admit liability.
When V prosecuted them in a tortious action, C tried to use the statute of limitations whose use it had claimed that it would forego.
V argued that it could not use those statutes, promissory estoppel preventing it.
The High Court said that there was no waiver
All types of estoppel serve the same purpose: “protection against the detriment which would flow from a party's change of position if the assumption (or expectation) that led to it were deserted”- From Walton.
The promise must relate to existing fact, NOT future fact or mere intention.
Furthermore the promise must be that the promisor will consider themselves bound by their promise: here there was no such indication, even though V may have wrongly interpreted it this way.
I.e. an objective test is used: what they are really asking is whether a reasonable person would consider the promisor to have bound themselves.