Giant sequoias: There are less than 80,000 of these redwoods left in California,

[speak easy]

19. The point is there are 500,000 redwoods in the the UK

not which species they belong to -

But there are more than just a handful of giant redwoods in the UK, and Wakehurst has many more than these three. The Victorians were so impressed that they brought seeds and seedlings from the US in such large numbers that there are now approximately 500,000 in Britain, according to a Forestry Commission estimate that includes coastal redwoods and dawn redwoods (a separate Chinese species) as well as the giant redwoods. Experts at Kew think most of the UK trees are giant sequoias, the official name for giant redwoods. California has about 80,000 giant redwoods, as well as also having coastal redwoods and a few ornamental dawn redwoods imported from China.

https://www.theguardian.com/environment/2024/mar/16/hidden-giants-how-the-uks-500000-redwoods-put-california-in-the-shade