Holding a genuine but mistaken belief that continuing to employ someone would breach immigration laws is a potentially fair reason for dismissal. The employer cannot rely on the permitted reason that statute prohibits continued employment, as its belief is wrong, but it can show "some other substantial reason" potentially justifying dismissal. The distinction is important as the statutory dismissal procedure applies to the latter but not the former type of dismissal, and breach of the procedure renders the dismissal automatically unfair. Where an employer believes there is a statutory prohibition on continued employment, it would be well advised to follow the statutory dismissal procedure just in case it has got it wrong. (Klusova v Hounslow London Borough Council, EAT)