Termination of employment - not so mutual?

In a recent general protections' case (Heriot v Sayfa Systems), an employee's dismissal by way of a mutual termination was held to be adverse action against the employee.

Facts

The employee fell ill at work, due to an undisclosed heart condition. He was absent from his workplace for nine days whilst he received medical treatment. On his immediate return to work, two managers of the employer met with the employee and terminated the employee's employment by way of a letter offering a payment and an opportunity to resign. It was described as a mutual termination of the employment relationship.

The employee signed his acceptance of the proposal put to him in the letter and subsequently commenced a general protection's claim against the employer.