The knife is 18 centimetres long; two thirds blade.

The split would be nearer 50:50 but the acrylic handle that marked it part of a table set is long gone. All that remains is the mis-shapen spike of black metal which formed its core.

This is Sharkmitts. It is my da’s tattie peeler and I hate it.

Sharkie owes its name to a previous owner, a three-fingered bad man who gave the knife to my da when he saved him from a two on one beating. Technically he didn’t deserve it since he was doing his job: warden at a men’s hostel. Sharkmitts, though, knew it didn’t work like that. Most wardens would let things sort themselves out.

My da, by his own admission, loved to get involved. Not tall, he was super-fit from months of climbing. He’d got a kick out of fighting as a kid and found the Warden’s Rules – never give a violent guest more than one warnings and hit them hard the second they put a hand on you – gave him an edge he liked. Plus he was sober, pretty much, and in the kingdom of the blind-drunk the half-cut man is king.

The way he tells it, picking his words with the same care he uses to slice the pile of potatoes, the first time he saw Sharkie was when he was getting the going over. He had heard about him. Dark mutterings about a well spoken man in his 50s far from home. A guy who said he’d lost fingers in a shipyard accident. Rumour was he had them cut off as a warning for putting his hand where it shouldn’t have been.

As a kid the ambiguity infuriated me. Again and again I would ask ‘What did he do?’, my mind conjuring up all manner of wickedness. But my da would only shrug. That was him. He wouldn’t make stuff up to scare me but wouldn’t sugar-coat it either. When he said he didn’t know exactly what the bad man had done, he just didn’t. What he knew was that he wasn’t going to let him get stomped outside the hostel.

What my da noticed straight away was that the attackers didn’t fight like hostel drunks. They were landing decent blows. He shouted at them to stop, pushed the nearest attacker when they didn’t and then, when pushed back, threw a right hook that toppled the guy. It worked because they backed off.

Sharkmitts, my da said, wouldn’t stop thanking him. Eventually he pulled the knife from his jacket pocket.

“He said ‘Here, have this’. I thought, ‘Great, a bit of rubbish,’ and it must have showed on my face because I remember he said, ‘No, this is a good knife. Keep it, it won’t let you down’. And it hasn’t….”

The last few words were always punctuated with a grin. He loved Sharkie. My mother did too. They’d squabble over it when they were doing the peeling.

In the end, my mother put me right. Da was out the back, harvesting tatties, and I was moaning about the peeler – again.

“Look, you hate it because you associate it with down and outs. He loves it because it reminds him of happy times. He was young and fit and having fun. Even the way he got it is a good memory. He helped someone. They said he was a bad man but he didn’t know that. They said all sorts in there.”

Now, her words roll around my head as I spin the knife in my hand and drop the peeled tattie into the pan, taking care not to catch my fingers because – even after all these years – it is still razor sharp and will cut for sure.

Less than half a room away, Shaun, my nephew, studies me.

After several silent minutes, he asks: “What are you doing with that old bit of rubbish Uncle K?”

“Nah, nah,” I say as, unbidden, the memory of an intruder caught and cut in the pale blue moonlight fills my mind.

“This is not rubbish son. This is a good knife. It never lets you down.”