Today marks the NHS’s biggest ever strike, with up to 100,000 nurses taking to picket lines. But why are nurses striking? And could walk-outs have been avoided? MailOnline explains all.Today marks the NHS’s biggest ever strike, with up to 100,000 nurses taking to picket lines. But why are nurses striking? And could walk-outs have been avoided? MailOnline explains all.Read MoreHealth News | Mail Online