The co-ordinated walkout was called by the three main ambulance unions – Unison, GMB and Unite.

All three are taking action on 21 December. GMB union members will go on strike again on 28 December.

Meanwhile, Royal College of Nursing (RCN) members are due to walk out for a second time on 20 December in parts of England, Wales and Northern Ireland, following action on 15 December.