A blast from the past: In my first ever job as an 'outdoor' Traffic Manager (think 'MOM" in modern speak) I had my first trespass incident to deal with. It involved three men spotted walking through a cutting on a diesel line in broad daylight. I decided to put an 'extreme caution' on and then met up with two local (not BT) police and we went to try and intercept them. We had just got to the top of a very deep cutting side when we spotted the three, just as a DMU came along at extreme caution. We shouted down to the men to stand clear, in the cess, which they did. Just as the DMU drew level with the trio one of them planked forward - dead drunk. The two coppers and I were convinced he was a goner. It happened too late for the driver to have seen anything.
The train crawled by, finally revealing the unconscious 'planker' who had his head nestled up against the cess rail. The wheels had gone through his hair!
It turned out that he was getting married the following day and had been on some sort of lunchtime 'stag do'. We got him off the line with his mates, suggested that he visited the barber before his nuptials and sent them off in a taxi. Didn't have the heart to arrest or try and prosecute them.
That was 45 years ago but it taught me a lesson that I never forgot.