Tried it also last year. Went quite smoothly with RoyalMail, although the photo ID verification was done with low quality selfies that bore little resemblance to my passport picture.
Then SWMBO tried it and failed. Tried again once or twice, making sure the photos were as crisp as possible and matched her passport hairstyle. Fail again. Tried another provider, failed again and gave up.
Gave me zero confidence in their verification process.