On the first day of action that has been earmarked, junior doctors will still staff emergency care. On the other two dates, they will walk out in the knowledge there will be other medics - consultants, staff doctors and locums - that can plug the gaps.

Whether that will be enough will be argued over ahead, during and after any walkout.

What is certain, though, is non-emergency services will suffer. Hip operations, knee replacement and routine clinics will have to be cancelled.

In fact, as happened the last time doctors took action in 2012, over pensions, expect hospitals to start rearranging services in advance.