Over the years, when this topic has been raised, I will now have posted this contribution three times…
Re guards on trains and the belief that they are utterly unnecessary...here's what happened to my wife on an evening train out of Waterloo a couple of years ago.
She found herself in a carriage with only two other passengers. One of them suddenly slumped in his seat and - being a first-aider at her work-place - she approached him and did what she immediately could to assist him, also alerting the remaining passenger.
She then set off to find the guard, in the certain knowledge that there actually was one aboard.
When she did find him, he immediately came to her carriage, assessed the situation and phoned ahead to the next station to get personnel there to arrange for an ambulance to meet the train.
The last she saw of her "patient" was him being stretchered off, presumably to hospital. Whether he "made it" or not she never found out.
Maybe one day, if YOU are one of the people who imagine guards are a money-wasting frippery, you'll meet a similar situation – either as first-aider or invalid – and just see what you think then!