Believe me my friend it is the operational problems that cause the overcrowding and havent you heard of the saying, there are statistics and statistics and damn lies.
Not quite in that way, but there are targets to be met which distort customer service. It's more financially advantageous in the short term to leave out a few stops and arrive at destination on time than to stop at all places scheduled. So witness things like the odd none-stop Paddington to Bristol service. In the medium term, of course, this puts the passengers inconvenienced off using the train next time, but I do recall listening to
FGW▸ 's Managing Director talking in person at about the time they had just won the franchise, where she was telling us that there are plenty more fish in the sea.
Big subject is customer loss / gain based on experiences ... I know there's a technical term for it but I've forgotten it!
I'm not in the picture on 125s, but I do know that FGW found they have far more maintaiance issues with the 15x units and 14x units than they had anticipated at bid time. And that the are looking to deal with them in the current refurb program. A lot of the issues / delays can be traced back to this, a lot to crewing issues, and a lot to external issues too.
Take the case of a train late at Swindon by 12 minutes and a passenger misses their connecting AND ONLY train to Melksham. That train may arrive at its destination just 6 minutes late having pulled back 6 minutes recovery time, that London service is not deemed to be late. Try telling that to the Melksham passenger.
As someone who regularly meet customers off the 19:08 arrival (the ONLY train on Mondays to Fridays with a connection from London), I now always have a mobile phone with me and ensure the customers have the number. It's proven oh-so-useful on too many occasions.
By the way - the theory goes that the 18:42 off Swindon should be HELD awaiting the London train that it's supposed to connect with, as it's the last train of the day ... the issue is more of a problem when
a) The 18:42 is cancelled
b) The connecting train is cancelled
c) The customer misses the train (due to tube problems)
d) The customer falls asleep and ends up headed for Parkway
(a), (b) and (c) - and the London connection being delayed - would be nothing like as serious were there additional trains off Swindon to Westbury. And in the case of (d) Parkway to Melksham is - well - and interesting journey that offers lots more opportunities for the customer to fall asleep and overshoot; "Stay there and we'll come and get you!" ...