My passport has just come through the door!
It was a really quick process, here is the timeline.
Application history
Passport delivered today (31st March around 1pm)
Passport printed. 11:38am on 30 March 2022
Application approved 8:55pm on 22 March 2022
Documents received 6:14pm on 18 March 2022
(* Royal Mail said old passport was signed for 15th March)
Application received 1:25pm on 12 March 2022
Application submitted 1:24pm on 12 March 2022