His name was put forward by descendant Renny Snell, who lives in Britain.
Mr Snell, speaking to the Times-Age from his Surrey home, said he got his ancestor's name in "fairly early in the piece, thank goodness.
"After about 10 days, I was biting my nails," he said. "There's been an overwhelming response." He got notice John Harold's name would be read out on Tuesday evening.
He and his wife attended the roll call at the tower, joining a crowd of around 500 outside.
They viewed one of the tower's yeomen walk into the field of ceramic poppies, an ongoing art installation in the Tower's dry moat, and stand on the mound among the poppies to call out the names at 8.40pm.
Mr Snell said it was an "evocative experience" which brought a lump to his throat.
A guardsman, who accompanies the yeoman, then plays the Last Post.
A check of the Tower of London website on Friday shows nominations are temporarily closed, with hopefuls invited to try again this week.
Mr Snell, who worked for Shell, left New Zealand in 1969.
He is a descendant of the two original Snell families of Leeston, near Christchurch, and describes himself as "a keen student of the Snell family".
John Harold was born in Leeston but was living in Kaiparoro in Wairarapa when he left for war on April 1915, according to the Lijssenthoek cemetery database.
Mr Snell said John Harold served in Gallipoli as well as the Western Front.
During a recuperation period in England, he married Ysabel Emslie, but Mr Snell believes he may have only seen his bride on one more occasion after the wedding, before he was killed.
Mr Snell visited the Anzac Bridge in Kaiparoro in the early nineties when "it wasn't in the pristine condition it is now".
The poppies are an evolving art exhibition called Blood Swept Lands and Seas of Red which will see 888,246 ceramic poppies 'planted' in the Tower's moat, to represent the fallen.
From the air, it appears as if the Tower is bleeding, an illusion heightened by suspended poppies appearing to 'gush' out of a Tower window.
The installation requires 8000 volunteers, with the last poppy to be placed on Armistice Day, November 11.
John Harold Snell is the uncle of Olympic and Commonwealth gold medallist Peter Snell, who visited the Anzac Bridge in 2007 to pay tribute to his Uncle Jack.
- additional information, Living in Kaiparoro, by Kay Flavell, Wairarapa Archives.