The ad, which was created to mimic the site content, served up another page, as adverts have a habit of doing. This page then served up its own set of adverts, scripts, pop ups etc. which at some point in the 'adception' chain resulted in malware ending up on the pc that was generating pop ups, fake warning messages etc. even with all browsers closed.
I used malwarebytes anti malware to remove it. I don't remember the version number.
I'm 100% confident that's where it came from as I got panicked phonecall about all hell breaking loose when he clicked on one of the stories. When looking at it with my dad later, he showed me the 'story' but it was a disguised advert. The pc only gets used for news and the BBC sport websites, something I'm confident of because of checking the history, which they don't know how to erase.
Thanks for explaining, I think you've confirmed however that it wasn't the regional news site and that particular ad slot which was responsible for the malware, although it was the start of the process. The same could be said for any website and link though, if you just keep clicking on links you will inevitably land on something bad if that is your intention, it doesn't matter where you begin.