Sometimes the wheels turn very slowly! So now I've just got round to being able to formulate the questions that have been rumbling around in the back of my mind for the last 10 days or so...
Really it's all about the maintenance regime. I remember you writing that the IEP sets and the Eversholt sets are on different - but related - maintenance cycles because of the differences in the respective contracts. But does this mean that all mechanical and electrical maintenance is only carried out at Stoke Gifford, North Pole and, to a lesser extent, at Maliphant? Can anything mechanical or electrical be done to the Eversholt sets (or even the IEP ones) at, say, Long Rock or Laira? Or is the only work done on sets which overnight at places like this cosmetic - possibly including toilet tank filling and/or emptying?
As I understand it the HST sets were effectively 'common user' - although they were allocated to a given depot for serious attention, if push came to shove then Laira could fix an Old Old set to keep the service running. From your description, and other reports, it seems that GWR has got itself lumbered with two separate fleets - although they are basically the same train - in the sense that an Eversholt set would not turn up on a South Wales working. It also seems to me that within the IEP sets, the nine car ones can overnight at places like Hereford, but the five coach sets all go home to bed at Stoke Gifford or North Pole.
It seems to me that considerable flexibility in the usage of the trains compared to the HST fleet has been lost.