European camping coincidence

In the late 1970s when I was a 2nd year student, I went hitch-hiking round Europe with a friend in the summer vacation. We arrived in Paris in the dark, and went to the very large campsite in the Bois de Boulogne (approx 400 pitches available in those days). We put up our tent in the dark (and rain) and went to sleep. Got up the next morning to find someone I knew from my school in the next tent. So I guess there is the compound chance of me choosing Paris to go to, the chance of going to that campsite and the chance of me pitching my tent next to the tent of someone who I knew, who had chosen the same week to go on holiday. There were probably about 300 people who had been at my school who would would have been about the right age to be on holiday by themselves in those days, and I suppose they would have had the same sort of chance of picking Paris/camping etc as I had. I estimate maybe 1 in 1200000 chance.