Why are junior doctors striking and how will the NHS cope?

The four-day walkout is said to be the most disruptive in the history of the health service

Some 50,000 junior doctors in England have downed their stethoscopes and picked up placards as they stage a four-day walkout in the bitter dispute with the government over pay.

Here are answers to some of the key questions on the strike action.

Why are junior doctors striking?