Hi @Diddleydo43 , just to update: we've now blocked this advertiser across our ad platforms, so you shouldn't see their ads on Mumsnet again.
You're right that a car seat which doesn't meet UK safety standards shouldn't be advertised here. We have filters to stop this kind of thing, but occasionally an ad slips through, so reports like yours really help.
If you spot any other ads that concern you, please post in Site Stuff with a screenshot and the link if you can. That lets us track it down and block it quickly. Thanks again, and thanks to everyone else on the thread for flagging it too.