BGP is the method in which various networks/ISPs exchange routing information with each other. Routing is how your ISP knows when you want to connect to an IP address, where that IP address exists on the internet. When you connect to 1.1.1.1, BGP is what lets the ISP know where to route that packet to in order to get to Cloudflare (who owns 1.1.1.1). The internet relies on BGP.
Unfortunately, it's susceptible to attacks. Numerous internet outages have been caused by BGP hijacking. You know those times every now and then when you lose access to large chunks of the internet, seemingly with no pattern to it? That's usually a BGP hijack. Often caused by a misconfiguration from some other ISP - but
occasionally caused by a nation state, it can mean anything from blocking your internet access to having all of your data routed through China (Without you knowing).
Anyway, Cloudflare is trying to secure BGP and have set up this website to track its progress:
https://isbgpsafeyet.com/
On that page there's a test you can do - and Virgin Media currently fails this test.
Now to be absolutely clear - most ISPs will fail this test today. But make no mistake, this is a serious issue and one that Virgin should work towards fixing - for your security and privacy.
(I've cross-posted this over onto
the VM forums).