Bert wrote:

As the first of the 'November 5th' fireworks are let off in the garden
adjoining my property this evening (and other bangs have been heard from
further afield), I was wondering what (if any) regulations are in force over
the letting off or possession of fireworks etc this time round?

http://www.dti.gov.uk/fireworks/public.htm

"It is an offence to let fireworks off between 11pm and 7am, except on
Bonfire Night (midnight), Diwali, New Year, and Chinese New Year (1am)."

Aren't we in the middle of Diwali now?

"The date of Diwali is set by the Hindu calendar and so it varies in the
Western calendar. It usually falls in October or November." [Source
BBC.co.uk]

I believe the festival lasts 5 days.