IWM description:BADGE, HIGHER FORMATION, SOUTHERN COMMAND (UK) - CORPS OF MILITARY POLICE (CMP)
"badge A shield divided vertically red left, black right, over all five white stars in the form of a cross."
Worth noting :
"The stars are a representation of the 'Southern Cross'. The colouring of the shield, and the stars, varied according to the arm of service of the wearer."
https://www.iwm.org.uk/collections/item/object/30071594