Live bullets were fired during a mock battle

The 22-year-old Grenadier guardsman from Sheerness in Kent, was killed three years ago after being hit by a live bullet on training ranges at Sennybridge near Brecon.

At an inquest, the army could not explain how live ammunition got mixed up with blanks which were supposed to be used during the exercise.

The MoD decided not to prosecute anyone over the death following a major investigation by Dyfed-Powys Police.

High court writ

But it has now begun a board of inquiry - an internal investigation to find how what went wrong.

The Health and Safety Executive has since demanded improvements into how range exercises are managed.

Private King's family say they are still unable to get the information they want from the army.

On Friday they will issue a writ in the high court in Newport, seeking compensation.

They believe it is the only way to get vital evidence released from the MOD.

As well as finding out how Private King died, the family also hope their action will help improve safety on Army training ranges across the UK.