Explain irrationality as a ground for judicial review under English law?

Under English law, irrationality, also known as "Wednesbury unreasonableness," is another ground for judicial review, which is the process by which a court reviews the lawfulness of executive or administrative action. Illegality and irrationality are separate but related grounds for judicial review, as both can result in a decision being declared unlawful by a court. The principle of irrationality as a ground for judicial review holds that a decision made by a public authority must be reasonable, meaning that it must be based on rational considerations and not be arbitrary, capricious, or fanciful. If a decision is found to be irrational, it may be set aside by a court, even if the decision was technically within the power of the public authority to make. The test for irrationality in English law was established in the case of Associated Provincial Picture Houses Ltd v Wednesbury Corporation [1948], where Lord Greene MR stated that a decision could be considered irrational if it was "so outrageous in its defiance of logic or of accepted moral standards that no sensible person who had applied his mind to the question to be decided could have arrived at it." In practice, the principle of irrationality is a high bar for a challenger to overcome, as the courts generally give a wide margin of discretion to public authorities when making decisions. Irrationality as a ground for judicial review is typically used in cases where the decision in question is particularly egregious, such as a decision that is arbitrary, discriminatory, or based on irrelevant considerations. It is important to note that the principle of irrationality as a ground for judicial review applies only to public authorities, and not to private individuals or organizations. Additionally, the courts will only interfere with a decision if it is found to be irrational, and not simply because they disagree with the decision or believe that another outcome would have been preferable.