We have become aware of connectivity by some of our users. As we have investigated these issues we have become aware that these users are on Sky Broadband (or a subsidiary). Sky have a message posted on their status page - https://www.sky.com/help/servicestatus/service-checker/broadband. This only relates to banking, however, a quick review of their forums shows other users having issues connecting to services and using VPNs.
We have raised this issue with the Sky Network Operations Centre.
=== Update ===
We have changed our network routing to avoid Sky, this should resolve issues with reaching us for users on Sky.