You woz lucky, on the way back, the customs burd in Le Havre, or was it Ouistreham? I forget, asked if I had any "bidons", she was asking everyone, I pointed to them lashed right at the front of the inside of the box trailer. not easy to get at. She asked if they were full or empty, so I said empty. She just let me go.I took three full jerry cans over to France when they had the strikes years age i was in a transit going on holiday with the family so i had enough fuel to get down to the south with a stop part way to meat up with parents, then on the way back fill them back up as it was all kicking of here, no one datterd and eyelid at customs
I did think about what I would have done if they had any in and they insisted on taking them off the trailer. i think I would have gone up and down the lines of cars and vans offering free top-ups until they were empty!