NATS is the only ANSP that has ever operated the "Swanwick system" which may also be referred to as NERC or the LACC system. It was part of that system which failed in 2014. I can't rule out a failure of that system as the issue this time but I would expect the regulations and operational effect to be different than they were. The En-Route operation has several different civil operations, all seem to have been affected but only one of those uses that system. There are several other systems in the Flight Data thread before it gets to the "Swanwick system". My money is on one of those. One of them is NAS which is only used by NATS in its current form. The others are variations of systems used all over the World.
I expect the CEO has spent the weekend locked in a room with a few people attempting the futile task of condensing a complex technical report into something the Secretary of State and the average Daily Mail reader can understand. Pointless really because the minister's catchy three word response written and the Mail editorial have probably already been written.