I could never forget Simon. He had all the physical attributes of Harry Enfield’s teenage character Kevin, but with a slightly more palatable personality. He was spotty, scruffy and prone to dramatics.

When he was in S4, we took a 36-hour bus ride to Venice on a social studies trip. After settling the pupils at the hotel, the adults nipped down to the cafe for a little relaxation. But we had hardly sipped our coffee when Simon appeared, distraught and breathless, shouting that a pupil had fallen off the pier and was drowning. We bombed it down to the pier, pulling off clothes as we went, only to find the lad sitting on the side laughing, wet up to his knees.

Simon had been the victim of a schoolboy prank and, by association, so had we. The next couple of days went by without incident, but on the third night, after we’d all gone to bed, there was banging at my door. It was Simon, again distraught, shouting that his girlfriend was about to take an overdose. I rushed along to her room, this time pulling on clothes, and trying to find out what Simon thought she had taken. I stopped when he told me, in all seriousness, that she had brought a two-litre bottle of mouthwash with her and he believed she was going to drink it.

I tried to avoid the lad for the rest of the trip because I found it difficult not to laugh every time I saw him. But on the last day, we were sitting just off St Mark’s Square when Simon was frog-marched over by two Italian policemen. He was wearing the only shirt he had brought with him on the 10-day trip, a brown Bri-Nylon affair open to the waist, revealing a bleached-white chest, and a pair of trousers that looked as if he’d done an oil-change in them. Unable to deny that he belonged to our party, we were told he was being arrested for being so badly dressed. They had a point; he was not befitting of his surroundings. Resisting the urge to wash him in one of the canals, I managed to sort him out so he was slightly more acceptable to the well-groomed Italian law enforcers, and drag him back to the hotel. The experience was enough to ensure I’d never forget him (and probably neither would Venice).

David Dempster is principal teacher at Boroughmuir high school in Edinburgh. He was talking to Su Clark. Do you have special memories of unforgettable pupils? Write to Sarah Bayliss at the address on page 3 or email sarah.bayliss@tes.co.uk