https://www.nationalworld.com/news/politics/brexit-british-beef-australia-trade-4556041
Earlier this month, a firm tried to export British beef jerky to Australia only to be blocked by border controls.
As 'colony breadbaskets', with lots of land and small populations, both NZ and Aus used to export lots of meat and other primary industry products to the UK.
I believe the UK's entry into the EEC and deprioritisation of the commonwealth led to those exports reducing and instead heading to Asia and the US.
Regardless, expecting to export beef to the other side of the world, a country with four times the cattle and a better reputation for food production, is just daft.
I don't think I've ever seen any UK-sourced food in NZ other than high-value small stuff like Worcester sauce, and expat reminder-of-home products.