So you are saying its fine, or its not fine?
I think what he's stating is that when you hear about London crimes you're always going to get more press than say Manchester crimes simply because of the number of people.
Even if the crime rate in London was lower than average you'd hear more about it because its by far our biggest city, and the one where most of the press and news companies have primary bases so they're able to cover things in far more detail.
My dad grew up in Newcastle just after the war, and from what he's said it wasn't at all uncommon for there to be a fair bit of knife crime, let alone the likes of the "mods and rockers" of the 60's...
Oddly people who like to push the idea that London is a hell hole and at record high levels tend not to be aware of how much knife crime there was going back even 30 years, let alone 60 years before modern reporting and easy access to news from outside your (very) local area. It's like a lot of crimes, you hear about stuff easily these days that 20-30 years ago you'd maybe have heard a mention of on the radio, and 40-50 years ago unless you were in the same town it was unlikely to have even made it into the papers.
And of course there is going to be an increase in reported and recorded knife crime in the last 30 years, they've cracked down massively on it and created new offences so things that 40 years ago wouldn't have raised an eyebrow now get reported, and things that 30 years ago would likely have gotten you a word in the ear get you prosecuted.
I remember when it was possible as a 10 year old to go into a store at the seaside and buy a knife*, now you can't even buy a bics razor for yourself until you're 18 (with ID to prove it, or about 30 without
), and they increased both the number of offences that are included in reported knife crimes, and how many of them got automatically prosecuted (pretty much any offence).
Hell I remember buying Stanley knife style blades for my dad in my early teens, these days as a teen you can run into issues buying plastic cutlery.
*I think I still have the scar on my thumb from that pen knife.