The High Commission of New Zealand in London (in Māori: Te Kāinga Māngai Kāwanatanga o Aotearoa i Rānana) is housed in a skyscraper known as New Zealand House in The Haymarket, London, off Pall Mall. As well as containing the offices of the High Commissioner, the building also hosts the New Zealand consulate in London and the military attaché.
Contact details can be found here
More information on the Wikipedia page [1].