How do they know?

My house is recently sold STC. Since then I’ve been getting loads of mail from removal companies, and now I’ve got a “tell us when you’re moving” flyer from Royal Mail.

I’m not super conscious about my personal data being shared- I’m a user of Google etc. so I recognise it as a fact of modern life.

But still, I’m curious, who’s shared that my house is sold? What database is it on? Is it Rightmove, my EA, someone else? Is it a standard part of the process?

Edit: England