This is a bit complicated.

The Department for Work and Pensions (DWP) is the government department that pays social security benefits in the UK. There are a range of benefits. Some of these benefits are for people who cannot work because of disability. In order to qualify for some of these disability benefits you need to have a medical assessment with an "independent" doctor. This doctor is independent from the patient. They're employed by companies who are paid by the DWP, so there's supposed to be some kind of arm's length arrangement there.

A doctor was employed by one of these companies to do this assessment work for the DWP. He was a committed Christian. He held that he would not be able to refer to people by anything other than the gender they were assigned at birth.

The DWP is clear: you must respect a person's choice of pronouns.

The General Medical Council (the registrant body for doctors in England) is also clear: you must not impose your personal views upon your patients, especially if it's going to cause distress.

This doctor was spoken to about his beliefs. He declined to change his stance. He lost his job. He took his employer to employment tribunal for unfair dismissal based on discrimination against his protected characteristic: his religious views.

He lost his case.

Here's the legal document: https://christianconcern.com/wp-content/uploads/2018/10/CC-Resource-Judgment-Mackereth-DWP-Others-ET-191002.pdf

It's pretty long! 42 pages! The last pages give a summary.

You'll notice the URL. He was supported by the Christian Legal Centre. I won't say anything about them, but I'll link this page which gives some useful information: https://nearlylegal.co.uk/2018/04/on-the-naughty-step-the-questionable-ethics-of-the-christian-legal-centre/