"That raised the eyebrows of the orthodoxy," Ms Herbert-Graves said.
"Bruce was a man ahead of his time, but he would also have been very comfortable in an earlier, more courtly time."
He had also had a huge impact on the Wai 262 fauna and flora claim. She had been asked by the late Del Wihongi to find others who could give traditional evidence from Te Rarawa at the first hearing, and Dr Gregory had been one of the first people who came to mind.
"Bruce's contribution to that was amazing; he gave such a masterful discourse," she said.
Another former Labour MP (and relative), Shane Jones, also spoke highly of Dr Gregory, who he described as a "major feature" of Maori life in the Far North in the 1960s and 70s, driving his Landrover up 90 Mile Beach to run clinics in the northernmost settlements.
His time in Parliament had been low key, but he subsequently played a role in gatherings of Tai Tokerau elders where he was known for taking often controversial positions.
"To give the guy his due, he firmly believed in te ao Maori, challenging the orthodoxy of the day, challenging themselves, challenging the Crown," Mr Jones said.
"He spoke at Waitangi on a regular basis. He spoke at all our big hui about the importance not only of Maori heritage but learning about your rights, defending your rights and using your rights."
Dr Gregory won Northern Maori for Labour in a 1980 by-election called following the resignation of Hon Matiu Rata. He held it until 1993, when Tau Henare won it for New Zealand First.