I also hate this bringing out of all the lovely, smiley brown people to perform for this goddawful family. I wish the people themselves wouldn't do it
Ngāti Rānana, who were the performers, have it as their mission to share Māori culture in London and beyond. They are phenomenal performers and role models and play a huge part in many annual and significant ceremonies both in London and worldwide.
Ngāti = Prefix for a tribal group
Rānana = London
You can see on their website that they are proud of their contribution at the service, "We are grateful to have these opportunities here in Rānana to showcase te ao Māori so far from home". www.ngatiranana.co.uk/
te ao Māori = the Māori world
Their founder, Esther Jessop, is an Officer of the New Zealand Order of Merit and was at the Queen's funeral. She spoke very interestingly about that here, and about the role of the monarch: You will see she is a very considered, thoughtful, intelligent woman as are all the members of Ngāti Rānana who I have met.
I don't think you need to worry about them anyone "bringing them out" without them fulling understand what and why they were there and it is quite insulting to assume they do not have the capacity to make their own decisions.