Sunday working opt-out: constructive dismissal claim fails after 18 years' service

A long-serving employee's resignation

Mrs Mason had worked for Wilko for 18 years when she resigned in September 2021. She had opted out of Sunday working in 2016, but from late 2018 she was rostered for Sundays about once every three weeks, losing pay for those shifts. Her grievances about this were rejected, and she resigned after her appeal was turned down, claiming constructive dismissal.

What the tribunal decided

The tribunal found that Wilko had acted reasonably. The Sunday working guidelines were introduced after consultation with staff and applied consistently to all opted-out employees. The reduction in Mrs Mason's hours from 30 to 25 per week was part of a wider restructuring (Project Horizon), not a punishment for opting out. Her grievances were properly investigated by managers who gave clear reasons for their decisions, and the appeal was handled by a different manager.

Why the claim failed

For a constructive dismissal claim to succeed, the employer's conduct must be so serious that it destroys the trust and confidence between employer and employee. Here, the tribunal decided that Wilko's actions were within the range of reasonable responses. The rostering changes were a legitimate business decision, and the grievance process was fair. The 'last straw' — the rejection of the appeal — was not unreasonable in the circumstances.

What this means for similar cases

This case shows that employees who opt out of Sunday working should not assume their hours will stay the same. Employers can make reasonable changes to rostering if they consult staff and apply policies consistently. It also highlights the importance of a thorough grievance process: if an employer investigates complaints properly and gives clear reasons, it can defend against constructive dismissal claims, even from long-serving staff.