“Statutory interpretation is an exercise which requires the court to identify the meaning borne by the words in question in the particular context.” (R v Secretary of State for the Environment, Transport and the Regions, Ex p Spath Holme Ltd[2001] AC 349 , 396). Words and passages in a statute derive their meaning from their context. A phrase or passage must be read in the context of the section as a whole and in the wider context of a relevant group of sections. Other provisions in a statute and the statute as a whole may provide the relevant context. They are the words which Parliament has chosen to enact as an expression of the purpose of the legislation and are therefore the primary source by which meaning is ascertained. There is an important constitutional reason for having regard primarily to the statutory context as Lord Nicholls explained in Spath Holme, 397: “Citizens, with the assistance of their advisers, are intended to be able to understand parliamentary enactments, so that they can regulate their conduct accordingly. They should be able to rely upon what they read in an Act of Parliament.”