What is your salary expectation?

If you’re in a permanent job interview cycle, do you know how much to ask for?

I’ve come across the following site recently, and while there could be some use, they don’t seem to have very much data from UK salaries.

https://www.levels.fyi/

The best source for salary expectation data, I’ve seen so far is Linkedin found behind their paywall for Linkedin Premium.

Do you know better sources?