Members of Managers in Partnership will be asked whether they want to join action being planned by unions including Unison, to which MiP is aligned, against changes to public sector pensions.

MiP members will be included in the Unison ballot, due to go out next week. This means that if Unison’s overall membership agrees to industrial action, managers will be permitted to join in – even if a majority of MiP members vote against it.

A Unison spokeswoman said: “MiP members will go into the ballot and if more people [in the overall ballot] say yes than no then action will go ahead.”

Over a million public sector workers are planning a “day of action” on 30 November, but the action –which may include strikes – could legally be sustained for longer.

HSJ understands many trusts’ strike contingency plans depend on managers being available on site.

Unions are challenging proposals to raise the retirement age for all workers to 66, scrap final salary pensions and raise employee contributions.

Talks are ongoing between health unions, the Department of Health and the Treasury. However, chancellor George Osborne has already signalled he backs the changes, which were recommended in March by the Independent Public Service Pensions Commission led by Lord John Hutton.

The Royal College of Nursing, Royal College of Midwives and British Medical Association have all ruled out industrial action for now, but have said they will support the “day of action” in other ways, such as holding lunchtime meetings.