Hi Fraser. Thanks for the reply.
No, I'm on 4.0.219, I'll update to see if that helps.
No big downloads at the time, couple of kids who will have been streaming something now it's school holidays, but my partner says it's been happening frequently when it's just her working from home.
Adblocker basically stopped it loading, I should have been more specific. Plus it was the same on all websites, Google included. Works fine with it off though, and wasn't always a problem.
Thank you