"Transparency is the bedrock of change"
... that's what Oliver Morley said the other day. He's the Chief Executive of DVLA and he should know. What users are experiencing now is not an outage. It's a bedrock.
Further, as you know, the great virtue of using the cloud is that capacity expands instantly to meet demand. As demonstrated in this case.
Who runs taxdisc.service.gov.uk? NSLookup says the IP address is 184.108.40.206. And RIPE says that belongs to Energis UK in Watford.