"It's really upsetting to think this can happen to someone you know," she told the BBC.
"All Grace was trying to do was live her life."
Tony Bennett, a family friend, added: "They're an amazing family, a very strong family. I'm sure they're going to get through this.
"It's lovely to see people come together and see how the New Zealanders have taken Grace into their hearts."
The English vigil came after vigils attended by thousands of New Zealanders in Whangarei, Auckland, Hamilton, Rotorua, Wellington, Christchurch, Queenstown and Dunedin.
Earlier this week, the English vigil's organiser David Heeney told local newspaper the Basildon Echo: "To the people of the world, if you don't know, a light was taken from Essex and we, as Essex and Wickford, weep for a soul taken away."
The local Thurrock Council held two minutes of silence in respect for the Millane family.
The Thurrock Gazette reported that Grace was the grand-daughter of a former mayor of Thurrock, Martin Millane, who died in 2000.