Update at 17:30:
We have suffered a primary link failure between two of our sites. Automatically, our backup links have taken the traffic, however this appears to be failing to achieve the expected throughput in one direction (inbound) and we are investigating the cause of this with the link providers. We are also migrating traffic to other links where possible, whilst trying to diagnose both faults.
We will continue to update you.
We will continue to keep you updated.