Telephone Call Coincidence

Summer 1973. I was living in a flat in Bedford which had a telephone and I had to attend an interview in Leeds. So, I thought I'd arrange to meet a friend who was living in Sheffield, on the way back from the interview. He had no phone at the last address I had for him there so I wrote to him and suggested that if he could meet he should telephone me on the flat telephone number, at 7pm on one particular Monday evening, and we could agree where and when to meet in Sheffield. So, at 7pm on that particular Monday I posted myself by the telephone, and within seconds of 7pm the telephone rang, and sure enough it was my friend on the line. After the initial exchange of pleasantries my friend immediately started talking about a sailing trip he had in mind. After a few minutes of conversation he had still made no reference to my proposed meeting and so I asked him if he had seen my letter, about stopping off in Sheffield; "What letter?" "I posted a letter to your Sheffield address about meeting up in Sheffield on the Xth, and I suggested you called me at precisely this time on this number to discuss it, which is why I answered the phone so quickly." "I left that address three months ago. I'm back home now in Bridlington, and I haven't seen your letter. I'm just phoning to see if you were interested in sailing." At which point I felt very odd. I can't remember if he already had my telephone number, which was unlikely, as I hadn't been at that flat very long, or if he'd got the number from my parents and called me. Either way it was very weird.