US here so nothing to do with any new UK regulations, but have to say we've ALWAYS gotten our residential mail no earlier than 2 pm. This is in various suburban areas. Sometimes it's 5:30 pm. I just want to know who is getting their mail first thing in the morning? I mean, somebody has to be. But it's never been our house.
I have noticed we have constantly changing letter carriers. Maybe that slows down newbies when they have to learn the route.
Anyway, as others have said, as long as we have such a reliable, honest postal service, it's not super important what time of day a batch of mail arrives.