There's another reason why 12-car Pendolinos are problematic. The original carriages are now around ten years old. If it was another two years before the twelfth carriages started to be delivered, there would be a big age discrepancy between the originals and the new arrivals. By 2044 the originals would be 40 years old and pretty well at the end of their lives; but coach no. 12 would be 11 or 12 years younger. Do you then scrap carriages which are under 30 years old? It's unlikely they could be reformed with any other units. In the meantime the owning ROSCO will charge a higher rental in order to recover the capital cost over a shorter number of years.
Someone can work out how many new carriages would be needed in order to reform all the existing Pendolinos into 12 car units and still have the same number of units in total as now. It would make turning class 460 into 458/5 look a simple job in comparison.
If we have HS2 which we shouldn't need longer Pendolinos.
Hence my suggestion in post #15 (which is useful for lengthening from 9 to 11 as well as from 9 or 11 to 12):
The other way to get the existing 9 coach fleet up to 11 coaches would be to buy more new 11 coach sets (say 14 new 11 coach sets) and shorten 14 of the existing sets to 8 coaches (slightly more seats than a pair of 4 coach Voyagers but slightly less than a pair of 5 coach Voyagers) and move them over to XC for use on their electrified lines (assuming we are talking CP6 or later that this happens) and use the removed coaches to lengthen the remaining sets to 11 coaches.
Although to get the whole fleet up to 12 coaches you would probably look at shortening the existing 9 coach sets to 6 coach sets to create the Mini Pedolinos, that would (assuming you shortened all 21 of the 390/0's) would give you 63 spare coaches, which would be more than enough to then lengthen all the 390/1's to 12 coaches long as you'd only need 35 (meaning that you could pick and choose which coaches you wanted in each set). Although that would then mean that there would be a need to purchase 21 new 12 coach sets to replace the 390/0's. This would mean that there was 1 more Mini Pedolinos than the number of 221's there are currently as well as providing more sets per set.
It then leads to the question, what is happening with regards to a certain large project and is the train lengthening required because said project is not going ahead or is it because passenger growth is higher than anticipated (as it has been so far) and we need extra capacity until such time as the project is completed?
