350/2 / 360 - Move them to scotrail convert all to 3 car replacing those 318/320's, The spare coaches could then move to SWR to convert a number of 450's into 5 car concidering they are very similar it possible that could be done. The 5 car 360/2 could also move to Scotrail for its possible Edinburgh - Newcastle commuter. Similar story could be said with 365's with the coaches added on to 465/466's
The problem with a 5 coach 450 is that you couldn't run it as a trio to make a 12 coach train for use in the peaks (where there's a lot of them), so unless you could limit then to routes where 12 coach trains weren't needed (but then a lot of these don't really need 4 coaches, such as Ascot - Guildford or the Lymington Branch, for most of the day) then they could cause more problems than they solve.
MK4 - convert them to a push pull with 67/68 in a shorter formation (Loco +5/6 MK4+ DVT) Send them to Wales long distance service/EMT Liverpool - Norwich/Cross Country however according to Modern Railways (Volume 75, Number 837) Colchester based MAN is offering to upgrade EMT HST to allow them to work with the mk4's.
Wales is already due to get some, some are due to be used on the GNWR services to Blackpool (both recently announced).
Liverpool - Norwich would be very slow over the fens due to not being able to run using Sprinter speeds. Also this is due to be split into two services over two franchises. With Liverpool - Nottingham possibly going to TPE and run by 185's.
EMT have been told that they need to have bi-modals on their IC services, so either a new loco or they would need to find routes that they could be used on which didn't go into London. Which would likely make such a suggestion unlikely.
EMT have also been told to ensure that they have provision for special events, so there could be scope for a rake or two on a low usage lease to cover Summer Saturday services to Skegness, football matches, events at Donnington Park, etc.
XC are possibly going to be told that they can use the 222's, however it would likely be cheaper for them to get some new 7 coach bi-modals and ditch their four coach units (or reform some to be 5 coach units) to obtain the same capacity. (I previously worked out that the 22x fleet would have to be at least 5% cheaper, probably more likely 10% cheaper, per coach to lease and run than a new fleet to even be in with a chance of competing on cost grounds, with the bigger discount possibly required to cover extra staff costs).
As such a loco and coaches wouldn't be likely, unless as a short term fix whilst the new units were being delivered. However, as soon after they start to arrive XC could start to run more and more services as pairs (at least over the core). Especially given the track access charges for a loco are eye watering, they even are pricy when compared to a 221 when comparing 10 coach trains. It's why most TOC's favour MU's.
I wouldn't be surprised if the Mark 4's kept popping up on different services to act as crowd busters or as short term leases at new franchises to tied them over until their new trains arrive. With several in service their lease costs should also be able to cover keeping the rest of the fleet available for use.
