An emotional hospital-bed email has revealed how the heroics of a Kiwi soldier who saved the lives of two comrades under heavy Taleban gunfire were inspired by his fallen commander.

British Army rifleman James McKie, 29, who is from Wellington, was still raw from the death of Corporal Richard Green when he joined an operation to push out insurgents from the notorious "fishtank" in the Afghan province of Helmand on Friday.

"We were very close and despite the fact he was my commander he treated me as an equal and often asked for my advice and guidance," he wrote to his family.

"I would have followed [him] anywhere. I was not there when he died but it was quick and he did not suffer."

Then, last week, under a hail of gunfire, Mr McKie, a 29-year-old soldier who was five months into duty with the 3rd Battalion The Rifles of the British Army, watched a hand grenade ricochet off unit commander Captain Graeme Kerr and land at his feet.

"I heard the fly-off lever come off, it was a sound I will never forget," he wrote.

"Instinctively and confidently I dived forward and picked up the grenade and threw it off the roof where it exploded about 2 feet [60cm] down in the alley below.

"We then extracted under a smokescreen and suppressing fire from my GPMG [general purpose machine gun]. Captain Kerr was unable to walk. I stayed out until it became clear that my wounds were badly infected ..."

Mr McKie has been hailed a hero by British and New Zealand military and is tipped to receive a British Army medal.

From Selly Oak Hospital where he is being treated for leg injuries, Captain Kerr said: "Bearing in mind you have about three seconds once it lands at your feet, half a second to make a decision, another three seconds to throw it ... that's pretty heroic in my book."

Mr McKie was hit in the face and arm by shrapnel fragments when the grenade exploded, mid-air, split seconds after leaving his hand.

"Recognition would be nice but making sure no one else gets killed or seriously hurt is my main priority," he wrote.

Mr McKie said it was ironic that the "good guys" died and "the guys nobody will miss don't even get a scratch".

Prime Minister John Key said Mr McKie had joined a growing list of New Zealanders who had demonstrated courage and bravery.

Last month, Victoria Cross recipient Corporal Willie Apiata was caught on camera with another SAS soldier in Kabul during an insurgent attack.

Tim Crowe, of the NZ Army Medical Corp who "bounced him on my knee" as a toddler at Waiouru Army Base and helped train Mr McKie as a medic, was proud of his student.

"It doesn't surprise me with James, even that he took some hits in the face." It took sheer guts to pick up a hand-grenade, he said.

"It's not like the commando comics - you've got to make a split-second decision."

As a rifleman in the reconnaissance platoon, you were the eyes and ears of the unit commander, Mr Crowe said.

"It's a risky job, that's where your good soldiers are in an infantry ... " he said. "You are the unit commander's eyes and ears so you have to be smart, have to got to be at the tip or cutting edge."

The young rifleman, who went straight into the NZ Army after graduating from Wellington's Tawa College in 1998, grew up at army bases around New Zealand and in Singapore, as his father, Andrew McKie, moved around working as a medic.

Mr McKie senior said he received a modest phone call from his son, but didn't realise the extent of his bravery until he read the email.

"What he did was pretty amazing."

BRAVE ENOUGH FOR TOP AWARD

New Zealand's latest war hero is unlikely to win the Victoria Cross, but is tipped to be awarded another top British war medal.

James McKie was probably in line for one of two awards, said Ministry of Culture and Heritage senior historian, Damien Fenton.

Those were the Conspicuous Gallantry Cross (CGC), which replaced the Distinguished Conduct Medal (DCM) as the second highest level of gallantry in 1993, or the third-ranking Military Cross, he said.

Mr Fenton said Mr McKie's display of bravery was "definitely up there" with British soldiers who had been decorated for similar actions.

He said more than 500 DCMs were awarded to New Zealanders, most recently in Vietnam, before it was replaced by the CGC.

Sixteen 16 CGCs had been awarded to British personnel for their actions during service in Afghanistan, and 14 in Iraq, Mr Fenton said.