Aspden v Webbs Poultry and Meat Group (Holdings) Ltd [1996] IRLR 521, QBD on 27th November 1995.

there can be an implied term in an employment contract to the effect that an employer may not lawfully terminate an employee's employment while the latter is absent on sick leave if that results in the employee losing entitlement to contractual sickness benefits (unless of course the employee's conduct entitled the employer to dismiss him summarily).

For relevant general notes see Illness, sickness and accidents and Implied terms in employment contracts/duties of employer