I've seen these Purdey, H&H, Westley Richards and others at SCI and Vintage Cup since the 1990s. I really don't think these firms make or sell very many bolt rifles. With exceptions they don't hold a candle to the best American rifles. WR are the nicest I've seen, and in the highest demand.
Another British firm that does quite a few bolt rifles has them made in Oregon on actions made in Arizona. They do ship them to London for proofing and enter them into the ledger books.
The same rifle ordered in Oregon without proof or ledger entry is a few thousand less expensive.