I'm not sure I fully believe those stats. I moved to the place I currently live in about 10 years ago. It's not a 'leafy middle-class area', but it used to be peaceful and felt safe nevertheless.
Two days ago a teen girl walking her dogs was approached by a man in his 20s, holding a machete in the park, in broad daylight. Luckily, she ran and escaped, he didn't chase her. But. About half a year ago, there was a man with two machetes, one in each hand, roaming the town centre, also in broad daylight. Haven't harmed anyone, but let's be honest, it's not very normal, right. Nothing much was done. A few days later he was seen again, with machetes. And arrested (finally). There were many more various knife related incidents, also stabbings.
I agree, stabbings obviously always existed. But say what you will, men/boys roaming with massive machetes in the middle of the day no less and hurting or at least threatening unrelated people - that didn't happen. Or men stabbing random people in the streets, completely unprovoked, unrelated to gangs, and not robbing them. Gang violence - sure, muggings - sure, but not like this.
Though I really don't think it's Starmers fault and I'm no fan of his.