Harrow Council has a special two week operation to help prevent and respond to the unsafe or anti-social use of fireworks during the autumn festive period.
Here’s a link to their site with information including how to report misuse. In particular you can call 020 4604 2775 between 7PM and 10PM (11PM on Diwali, November 8th).
Their page states that it is against the law to set off fireworks, including sparklers, in a street or other public place. This includes public parks and open spaces. So if you see people setting off fireworks in any Harrow nature reserve, and it is before 10PM, call 020 4604 2775. After 10PM there’s only an on line reporting system.
It’s not relevant to nature reserves, but the council page also states that it is illegal to set off fireworks anywhere, even on private land, after 11 PM, with the exception of Bonfire Night (November 5th), when the cut-off is midnight, and New Year’s Eve, Diwali (November 8th) and Chinese New Year (6 February 2027), when the cut-off is 1 AM.
Image by Scott Davies; Creative Commons licence