The Minister of State for Immigration (Damian Green): The Immigration Rules specify that the detail of how certain requirements will be applied will be set out in UK Border Agency guidance rather than in the Immigration Rules themselves. This is essential best practice as it enables the UK Border Agency to have the flexibility it needs to make minor changes whilst staying within the framework set out in the Immigration Rules.
However, on two particular points successful legal challenges have been brought to the extent to which requirements must be set out in the Immigration Rules rather than UK Border Agency guidance. The first is the minimum levels of courses that may be studied under Tier 4 (General). The second is the periods of time that applicants must have held available funds for.