P bought property with some waterways that he thought were private. The Navigation Authority, assuming this to be correct, allowed her to erect signs to this effect, before later concluding (and the court agreed) that public rights of navigation existed over those waterways. P tried to argue that she had a LE and that the Navigation Authority could not frustrate this LE by demanding that the “private” signs be taken down. CA held that the words and actions of the defendant's representatives had been sufficient to give rise to a legitimate expectation and that an expectation relating to property could be a "possession", the peaceful enjoyment of which was entitled to protection under article 1 of protocol 1 of ECHR. However, because the authority had acted proportionately in demanding that the private signs be removed the convention right did not render its actions unlawful. However the declaration granted to the authority would be amended so that in exercising its statutory powers it had to take account of the common assumption previously held by both parties that the stretch was private.
Peter Gibson LJ: P accepted that “a LE can only arise on the basis of lawful promise or practice”, and since the authority couldn’t lawfully get rid of public rights of navigation, her claim would instantly fail, but for the existence of an ECHR right.
May LJ: “orthodox English domestic law does not allow the individual to retain the benefit which is the subject of the legitimate expectation, however strong, if creating or maintaining that benefit is beyond the power of the public body.” He considers this an unfair outcome, but is bound by precedent. This necessitated the invoking of the ECHR.