Hospital admissions are reliable indicators for violent crime and stabbings in particular - if you get injured you're going to need a doctor and they will record it - and these are going down [1]. There is little to suggest any kind of epidemic or increase in violent crime is going on and the stats on this seem to play out.

What is more of an issue is more antisocial crime such as street robbery or shoplifting. These crimes are much more likely to be snatch and grab, with no violence involved. They still have an impact on the victims but they're not making the city significantly more violent.

[1] https://www.london.gov.uk/london-records-fewest-homicides-ye...