Mobile phones are amongst the easiest things to deal with. Times I have found them it was easy to text from it to get the owner to hook up, were the owner not frantically calling the phone already.
Once I was on the Thameslink from Luton into London with an actor friend. The conductor fined him for having an 'invalid' ticket, even though it was clear he had merely discarded the wrong part of his return ticket. I showed my ticket, bought the same date & time, for our northwards journey, a week earlier, yet the conductor went ahead and made him pay the penalty fare. He suggested that he did not make the rules, besides if he was to listen to what people had to say everyone would be travelling for free.
As the fat git made his way off up the carriage I noticed he had dropped a roll of notes, I lent over and reached to pick it up. Cupped it in my hand. Minute or two later the conductor was back down the train peering from side to side under the tables.
When he got to us I held out the roll to him.
I then asked if he still considered that we might be the type of people who were concerned with diddling Thameslink out of a tenner?
He was rather embarrassed, and handed Matt a form to claim the fare back.
£20 is about my lower limit these days.
Back in my youth I was drunk on the tube and notices a lassie fast asleep with a tenner at her feet. I picked it up and tried to wake her, that took me several stops and then found out it was hers. I was now at the wrong end of the tube line and it was the last tube, so I ended up staying at her place. Honesty pays.