The state of the trains
The state of the food on the trains
The punctuality of the trains
The frequency of the services
The reliability of the trains
The attitude of the staff
The stations and the station facilities
It was all absolute garbage mate. You've clearly forgotten. Do you not remember the jokes about British Rail catering and utterly fucking awful it was. Do you not remember the jokes about the late running of the trains? They were a total laughing stock. Take your rose coloured glasses off.
Not with a little irony, I'll link you a Guardian (of all newspapers) article, "Forget the nostalgia for British Rail – our trains are better than ever". When even a lefty rag says a privatised service is better than ever, maybe people should reflect upon it.
https://www.theguardian.com/commentisfree/2013/aug/15/nostalgia-british-rail-trains-better