Basically the 805s are taking the WCML duties from the 221s. The 807s are to bolster the electric fleet where 9 or 11 car long services are not needed. That seems to be Blackpool but also the second service every hour to Liverpool. Scotland retains Pendolinos and istr that the 805s & 807s will not be running North of Preston.
That’s not entirely correct. First of all, the 807s are not just there to bolster the electric fleet, they are also to replace the Voyagers (there were 20 of those and 13 805s), and it’s worth pointing out that the 807s actually have equivalent (if not slightly more) standard class accommodation than a 9 carriage Pendolino anyway. The routes 807s work on are nothing to do with their capacity.
Everos are supposed to work the hourly slower service to Birmingham, not because 9 or 11 car services are not needed, but because Voyagers didn't just work to Chester and North Wales, they had a handful of services to Birmingham, and a handful of services to Scotland via Wolverhampton. An internal reshuffle a few years ago meant that a good few Voyagers replaced Pendolinos on Birmingham terminating services, allowing the Scotland services to become 100% Pendolino operated.
Then, it was made so that the stopping pattern - which was 1tph Birmingham calling at Watford then Coventry, 1tph Birmingham calling at Rugby then Coventry, and 1tph Birmingham (continuing to Scotland) calling at Milton Keynes then Coventry - would change so that 1tph Birmingham would provide all of the hourly calls for Watford, MKC and Rugby, and the other two (one continuing to Scotland) would be non stop.
Considering the 80x have better acceleration than the Pendolinos, and can't take advantage of tilt acceleration where it's best needed up in Scotland anyway, it was decided to make this stopping service Evero operated.
The 807 order was larger than it needed to be to cover Voyagers to allow for a second Liverpool service each hour, and this is why they've started to appear on Liverpools in place of 9-Pendolinos.