Thanks for your contribution, Kempie.
Back in the 1950s and 60s, when I was growing up, my parents always stated that it was illegal for ice cream vans to sound their chimes after 7pm. (I have no idea whether this was based upon my parents' knowledge of national laws, local byelaws, or simply 'what they'd been told'). When I searched for the relevant legislation, I was fully expecting to find confirmation of the 7pm cut-off, and I was surprised that the only statutory requirement I could find related to 9pm.
It's interesting to note that your link goes to a 'Code of Practice', rather than to any specific legislation. Perhaps that code is akin to the Highway Code, in that it has no direct legal standing but it can be referred to when determining whether an offence might have been committed?
Chris