Does "explore segments" only retrieve *my* segments?

I'm trying to use the API to discover local cycle routes to try out. I'm trying with a GET request on "explore segments":

https://developers.strava.com/docs/reference/#api-Segments-exploreSegments

But it always returns an empty segments array []

Here's a sample query (enclosing roughly the entire UK in the bounds):

Am I wrong to expect data back? I've only just signed up to Strava so I have no data of my own yet - does "explore segments" not return "public" data?

Thanks,

A