It's a BBC show. Do ratings matter?

To an extent they do, but Doctor Who is safe as houses and still one of the BBCs most iconic franchises by far. Viewing figures decline but so it goes for most BBC shows now due to the rise of streaming.

Ratings do matter for BBC shows, but they're only one of the many factors involved. For example, the Audience Appreciation Index matters just about equally to ratings for most programming. And the BBC being a public service broadcaster, it can continue to broadcast shows that serve a public interest -- even a minority public interest.

For example, the BBC has been broadcasting shows such as The Sky at Night for decades, which has very small audiences. A commercial broadcaster would have ditched it a long, long time ago.

The BBC absolutely isn't a commercial broadcaster. It doesn't carry advertising, so it isn't reliant on maximising the value of its advertising.

That said, popular prime time shows such as Doctor Who would be sidelined or axed if their ratings fell too far and remained low over a period of time, because they're expensive to make and a public service broadcaster needs to be sensible with its money.

But Doctor Who is in no danger. Its recent ratings have been fine -- comparative to other popular BBC shows (rather than comparative to figures it used to get two decades ago, by which metric all shows are doing badly) -- and it's a cornerstone of British popular culture.

If worst came to the worst, Doctor Who would only be rested. There is no real prospect of it being cancelled outright again, because it's one of the corporation's most valuable properties.