What is the meaning of “person aggrieved” in legislation?

The expression “person aggrieved” (or its equivalent "aggrieved person") is commonly used in legislation for the purpose of identifying those legally entitled to contest a particular judicial or administrative decision. The quoted expression is generally understood to refer to any person, other than “[…]a mere busybody who is interfering in things which do not concern him […]”, who has a genuine legal grievance because an order or decision has been made that affects his or her interests in a prejudicial manner (see Attorney-General of the Gambia v. N’Jie, [1961] 2 All E.R. 504, at 511, P.C.). It is also generally accepted that the expression, in its ordinary sense, is broad enough to include a party to proceedings, such as Co-op in the case at bar, whose rights are directly and prejudicially affected by an order or decision.