A Nottinghamshire police officer who was killed after being dragged by a stolen car was among those being remembered on Sunday.
National Police Memorial Day is held to pay respects to officers who lost their lives while on duty.
Prince Charles and Home Secretary Theresa May were expected to attend a memorial in Belfast.
Dog handler PC Ged Walker was killed in 2003, after he was dragged by a stolen car through the streets of Bulwell as he attempted to remove the keys.
The memorial day has been held every year since 2004, with a national service being held in different cities in the UK.
