Except that the line was created with diesel traction in mind and that the trains in the legends pack did run on the line historically. At present, you would only be able to use the Class 800 series in diesel mode as the OHLE is modelled as far as Heathrow Junction but not functional. It is usually quite easy to have past trains on routes, ie before the era in which it is set, but often more difficult to include newer stock as some of the changes to infrastructure that are required are not modelled because they didn't exist at that time. We will most likely get the Class 800 series if we get a more recently modelled section of GWE. As for the Paddington to Reading stretch, this is from 2015 and anything more recent than that won't happen.
