Now you are being silly. 222s can be reformulated to any length from 3 to 9 cars; depending where the fleet is cascaded to, the TOC can reallocate as the mood takes them.
It's really not that simple, you could end up with half of the remainder as 12 car formations.
Up to a point; you are making the standard error of trying to set service patterns according to stock, rather than allocate stock according to need.
Just because the numbers fit is not a good enough reason to justify a particular solution. Start with service needs, THEN decide where the stock could/should go.
OK then lets assume that I can't send any to GW or EC, lets do some more numbers here...
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Well, assuming a maximum 10 car formation and that you can shouehorn a transformer big enough into a 5 car formation to make it 6 car, there is space within the 222 fleet for...
21 6 car EDMU
2 9 car EDMU
4 8 car EDMU
Or with more sensible transformer sizes, requiring two per formation, would yeild...
17 7 car EDMU
6 10 car EDMU
4 5 car EDMU
Or with a bit of shuffling...
18 8 car EDMU and 9 5 or 6 car EDMU depending on transformer specs.
Now, working on my 'silly idea' for re-moddeling Oxford Road going though...
Post Northern Hub and NW Electrification one assumes TPE will need 48 daily diagrams
MIA - NCL = 8
MIA - MBR = 8
MAN - HUL = 5, Assuming extention to LIV/CTR = 7
LIV - SCA = 8
TPE N = 31
Add on the extra 2tph between MAN and LDS as part of the Northern Hub, 4 or 5 diagrams, assuming some slack, 5.
TPE N = 36 dia.
TPE S = 8
TPE NW Diesel (MIA-BIF/WDM) = 6/7
Thats about 51 diagrams to cover with Diesel units, assuming no doubling up of services, that fits quite nicely. Now lets inject the 222 fleet into the equation.
Assuming a 6 car max formation (and ignoring for the moment that a 6 car 222 has less capcity than a 6 car 185)
Sending all the 6 car units over to TPE would mean being able to convert all of the High end ECML (NCL and MBR) services to 222 operation where they can make use of their higher top speed. Allowing another 16+ diagrams to be doubled up out of the 185 fleet. I'm thinking peak hour diagrams through Bolton, Leeds, and some of the extra 2tph. And all turbostars would say bye bye to another TOC.
The remaining 8 and 9 car units, well keep them with EMT to run off wires services to say, Lincoln and York/Scarbrough.
If we go for the 8 car option that would mean my hairbrain scheme of rebuilding oxford road station going thorough, one could not only send all 222 units to TPE, TPE could also take on an additional route, or again, keep the remaining 5/6 car units with EMT to run off wires services.
Adding the extra route into TPE would be Liverpool - Norwich, run either by 185 or 222 units, but with an extra 11 units floating around in the fleet ontop of what is needed for the rest, even with a load of slack and doubled up diagrams through the core, would take over Liverpool - Norwich quite nicely.
When TPE N is electrified, TPE would gain a fleet of 4, 6 or 8 car units to operate the core route.
The 185 fleet could then leave TPE wholesale and they would continue to use their 222 fleet for off wires services including TPE South. And windermere / barrow.
This would be with a fleet of 27 units, plenty to run TPE South, Liverpool - Scarbrough and possibly Liverpool - Norwich aswell.
The 51 185s would be able to find a nice home either with SWT, Scotrail or ATW.
So the numbers work nicely for TPE, work much nicer with platform extentions (or extensive use of SDO at Oxford Road on all services)