Do you have direct experience of boarding a train at Marylebone at the country end of the station after the engines have shut down and the train is in darkness? If not, I'd suggest you are not in a position to comment how dark said train would be.
No. I do, however, have quite a bit of experience of being on trains with no lighting in other locations, including at locations rather more secluded than Marylebone. In any case, if we are saying that levels of ambient light there are so bad, surely it would be possible for the platform lighting to be uprated?
What kind of modification would prevent the lights switching off due to the condition of the batteries?
In the first instance, maintaining or replacing batteries better? Finding the root cause of why the batteries are degrading so quickly in the first place? Fitting dedicated batteries that simply supply a minimum level of emergency lighting? A shore supply arrangement? To be honest it’s pretty undesirable for carriages to be being plunged into so-called “pitch black” potentially as soon as an engine stops. What would happen if an engine stopped on a train detained anywhere in the darkness, or even worse in a tunnel?
Or maybe a solution would be to not allow passengers to board until the engines have been started and interior lights switched on...
Yes, that’s a solution. However it’s also one which is clearly pissing off the end user, so it certainly isn’t an optimal one, or even a good one. If this is the best Chiltern’s management can do then maybe they’re also sub-optimal.
But then I’ve always found Chiltern to be like this - they’ve always been very good at giving it the “holier than thou”, but the experience on the ground doesn’t always match the hype. Quite often dirty and rattling trains with broken interior fixtures, a focus on end to end journeys and seemingly little care for many intermediate destinations, and their best speciality of all which is 2-car trains on busy services. Hence I’d always pick West Coast for London to Birmingham journeys.