Percy Shears, 77, from Croydon, has become something of a celebrity in his neighbourhood by holding "drill music" parties in his shed. He regularly hosts dozens of teenagers on Saturday nights, and police often visit for fear that they might turn violent.
One policeman explained, "Drill music is a form of rap music so dangerous that it makes MC Hammer look like the Pope. And I mean the last Pope!" He paused for a moment, then said, "Wait, let me think and try to work that out. Maybe I mean the current Pope. I mean whichever one would make drill music sound more dangerous. It's very confusing."
Mr Shears began holding parties about a year ago. "I'm just like Frankie Valli when I get up there," the balding former gardener said. "I set up me toolbench, and start to power up me Black and Decker. Sometimes I'll sing along too, although we call it 'rapping'. I like gardening so I often rap about me hoes."
It is hard to imagine a genteel pensioner like Percy leading gangs of youngsters in freestyle rap battles in his shed. He explains to me how the strange habit started. "It were soon after me dear Peggy died. I was in me garden, revving up me Black and Decker, and completely forgetting meself in the rhythms of the motor in me hand. I totally forgot where I was. Just then some passing youths told me that they loved the sound I were making."
"They said, it was just like their favourite singer - what's his name? Showery? Or is it Punchy? I don't remember too well." Before long, Percy was performing regular gigs in his shed, and sometimes he even lets the kids have a go with his drill-set.
He has no plans to stop holding the sessions, but he admits he still doesn't understand the music scene fully. "I don't know half the words they are saying. Well you know what slang is like. I still remember when they invented the word 'groovy'."
Percy said that he gets on well with his visitors, although it hasn't been without its own risks. "Sometimes they get carried away," he says, showing me a scar on his arm, "They'll get too excited and drop the tools by mistake. I've been stabbed nine times now. I have to keep telling them to be careful."
"Also they're always asking to borrow me secateurs, but I don't mind. I'm just glad to see so many young chaps getting into such a traditional hobby as gardening. When you hear about what some kids get up to... ooh, it's awful, in't it?"