King Tuheitia has appointed a tribal outsider to represent him on Tainui's executive board - a move which has been criticised because of the appointee's relatively recent connection to the Kingitanga.

Gregory Miller, 45, is the group general manager of freight company Toll New Zealand. He said he hoped to prove his value to the movement's followers.

Mr Miller fills the kaahui ariki position left vacant when Lady Raiha Mahuta died this year.

Her husband, the king's uncle Sir Bob Mahuta, was the representative for the late queen, Dame Te Atairangikaahu.

The tribe has assets worth about $500 million. Mr Miller will have full voting rights on the executive board, which also has of 10 tribally elected members.

Mr Miller said he met Tuheitia 20 years ago when he was a storeman and Tuheitia was driving trucks.

Their paths didn't cross again until Mr Miller provided a train for kaumatua and kuia to travel from Ngaruawahia to Taupiri Mountain for the burial of the king's mother, Dame Te Ata, in 2006. The pair have kept in touch over the past four years and struck up a close relationship, he said.

"From there our relationship has evolved. It's definitely a friendship, but one of respect. He approached me to support him and help with his role and that has occurred in the last few years. I've taken an active role in getting a structure around him that's conducive to supporting the king.

"He's reached out for me to help him in a range of ways," Mr Miller said.

In a tribe that has traditionally appointed important positions from within its own ranks, the decision, which Tuheitia revealed to tribal members at their Te Kauhanganui parliamentary meeting at the weekend, didn't go down well with some.

A Tainui representative who was at the hui said people felt "gagged" from challenging the king directly about the move because of respect for his office.

"You could have heard a pin drop. Nobody said a word. He ended his speech and then he left. But one of the members asked Tuku [Morgan, the executive chairman] 'who is this fellow? What's his whakapapa?'

"He told us 'I don't know. He's the CEO of Toll.' Without question there was disgruntlement, people were not happy."

Another tribal source said he would be paid $35,000 as a kaahui ariki board member, and the decision was crazy. "[Mr Miller] is viewed as a Pakeha, no one knows who he is or where he's come from. What does he know about the Kingitanga?"

Asked about the criticism, Mr Miller, who has Ngapuhi, Rongowhakaata and Ngaiterangi ancestry, said he hoped he wouldn't be judged before he really got stuck into his duties.

He also hoped Tainui people would trust and support the king's decision.

"It's his decision, that's probably the key thing to say about that. His decision hasn't been made lightly or easily."

The announcement comes close on the heels of the leaking of a document known as the King's Charter which sets out a 10-year vision for Kingitanga - the first real stab at a vision for the movement under Tuheitia's stewardship.

It was partly put together by former Prime Minister Jim Bolger's chief press secretary and broadcaster David Beatson, who is also Mr Miller's stepfather.