Corporal Grant's widow, Tina, is also in the Defence Force.
Defence Force chief Lieutenant General Rhys Jones said Corporal Grant was a "competent and likeable" soldier who had, after an initial stint, left the SAS because he wanted to focus on his family.
However, after consulting them, he asked to come back into the unit "because that's how he saw himself - as being an SAS soldier from the start to the finish".
The decision was made "knowing that the probability of further deployments was on the cards".
Yesterday, Corporal Grant's family said he was "a determined person, some may say stubborn, in his pursuit of his goals while growing up".
"He wrote in a school essay once that he wanted to be in the SAS; he worked towards that goal from that time onwards and convinced the army he could do the job."
They said he "had absolute faith in his friends and colleagues and what he was doing in Afghanistan".
Last night, a woman told Radio New Zealand how Corporal Grant had pulled her car out of the mud and how he and his wife had started a neighbourhood watch group in the tight-knit Tokomaru community.
"He and Tina were very active [in it]. They even organised a barbecue where we could all get together and discuss what we wanted the neighbourhood to be.
"He was friendly and a very intelligent man. Interesting to talk to."
Another Tokomaru local remembered Corporal Grant as a family man.
"[He was] very friendly and a wonderful community man and just a very nice man to know.
"We just really feel for Tina because she's such a lovely lady too, so friendly. And the kiddies are just lovely. It's just tragic. I don't know how they're going to get on without their dad and Tina without her husband."
General Jones yesterday provided further details of how Corporal Grant died.
He had climbed on to the roof of a building next to the British Council compound to co-ordinate fire and provide other information to the Afghan Crisis Response Unit that was to move into the building to free three British and two Nepalese Gurkha hostages.
He was hit with a rifle or light machine round which entered the armhole of his body armour and pierced his torso, hitting his heart.
Despite his injuries, he clung to life for some time and was resuscitated at least once. However, he died during the helicopter flight to Bagram Military Hospital.
Corporal Grant had spent a third of his 21-year military career as an infantryman and a further third with the Royal Engineers.
The rest had been with the SAS, an outfit he had "the most personal identity with", General Jones said.
Corporal Grant was also a member of the Patriots Defence Forces Motorcycle Club, whose members are drawn from former and current members of the armed services. In 2010, he was a road captain in the White Ribbon Ride campaign to end violence against women.
"It's shattering when you lose someone like Duggy," said Patriot and ride spokesman Shane Henry.
He described him as "a real bloke who was not afraid to stand up against family violence - who served his country, both in and out of the uniform.
* Prime Minister John Key said he would not bow to foreign pressure to keep the SAS in Afghanistan longer than March - but would not rule out future deployments.
Britain's special representative to Pakistan and Afghanistan, Mark Sedwill, is due in New Zealand this week but the Prime Minister said Mr Sedwill would be wasting his time if he tried to lobby for an extended tour.
