A 'one-in-a-million' Norfolk-based soldier was killed by a huge roadside bomb hidden less than 25 metres from an Afghan National Army sentry post which had been left unmanned, an inquest heard on Monday.

Father-of-three L/Cpl Richard Brandon, 24, died instantly when the blast, which occurred as Afghan forces were conducting a change-over of troops, ripped his Samson recovery vehicle in two in September last year.

Ruling that L/Cpl Brandon was unlawfully killed while on military service, coroner Robin Balmain said it was a matter of great regret that the sentry post was left unmanned by the ANA.

The coroner concluded: 'In order to keep this area as safe as possible, there are - or are supposed to be - consistent observations along the route.

'It was their (the ANA's) function to observe the route where the explosion took place and for whatever reason that was not done.'

L/Cpl Brandon, known as Richie, joined the Army in 2001 and was a member of the Royal Electrical and Mechanical Engineers and was attached to the Light Dragoons at Swanton Morley, near Dereham.

After his death his colleagues described him as 'legendary.'

His fiancee Emma Jayne Webster said: 'Richie was a wonderful fiancee and father/stepfather to Martyn, Liam and our daughter Kaitlin.

'He loved his job. I feel privileged to have spent four-and-a-half years of my life with him. He was one-in-a-million.'

Colleagues of L/Cpl Brandon told the Black Country Coroner the attack in the Babaji district of Helmand province left an eight metre-wide crater in the road, in clear view of the ANA sentry post.

Captain Robin Smith told the coroner that the pressure-plate bomb exploded at about 5.30pm on September 2 last year, shortly after a 70-strong contingent of Afghan troops left a nearby compound without conducting a 24-hour 'hand-over' to the 100 Afghan soldiers who replaced them.

Capt Smith, who was stationed at a patrol base around a mile away from the blast, said of the sentry post: 'Up to that day it had been manned by the Afghan National Army.

'The old troops that were manning (the compound) and therefore the sentry post had left that day in the daylight, which we weren't expecting them to do.'

L/Cpl Brandon, from Kidderminster, Worcestershire, was driving the Samson to the ANA compound to collect a generator and was one of three soldiers travelling in the Samson, which landed upside down after the bomb detonated.

Medics arrived at the scene within minutes and treated a soldier who spent a month in a coma after the explosion, which scattered parts of the Samson - including its engine block - up to 100 metres away.