Have to be honest mate, I've always felt safe in London, and certainly a lot safer than some English Towns. I think what also helps with London is what I see as a high Met Police presence, whether you trust the cops or not is another matter, but their visiability to visitors and tourists is reassuring. I don't feel that crime is any higher than any other location I visit, and considering London is our major capital City that's impressive. Obviously I'm not there to scratch the surface and it will have it's problems. Whether you are in London, Canterbury, Manchester, Liverpool, Cardiff, Glasgow, those problems exist. I don't think there is anything that particulalry makes London stand out as the worst.
Got me thinking about the most populated cities now, so top 100 in 2022, you need to scroll down and it's 2 pages. 72 Canterbury...lol so quite way down on the list, Maidstone 66, Rochester lost it's City status I believe. Brighton 32. London easily number 1. https://www.ciphr.com/infographics/biggest-cities-in-the-uk-by-population