@Baldimo,
Your proposal of making weapons legislation not apply to people over 40 is typically dunderheaded. Legal age restrictions are applied because as people grow from children into adulthood, they gain the judgment to perform certain important tasks at different ages, until they reach full legal adulthood at 21. So we allow them driver's licenses at 16, voting at 18, alcohol at 21, etc. However, once you reach adulthood, you get put into the same pool as everyone else until such time as you qualify for Social Security and Medicare, which are essentially government run insurance systems the person has paid into their whole working life anyway.
Your foolish suggestion would break the age of adult privileges from over 21 to 21-40, then 40 on up. For no discernible reason. The only purpose of such a law would be to piss off those people between the ages of 21-40 and set them into opposition to those over 40, which would doom the bill. Sorry, adulthood remains adulthood, we don't want to go down the path of allowing some laws not applying to you if you are over 30, others not apply to you if you're over 35, other not apply to you if you are over 40, etc.
I'd hate to think what would happen if we started applying such laws to other situations besides weapons. Like maybe sending people to jail for embezzling over a million dollars for 7 years if you are between 21-40 but for only 2 years if you are over 40 because, statistically, you have less time left before you die. The entire legislative and legal system would collapse.
Any other brilliant observations you care to make about the right of Londoners to control their spike in knife attacks?