For those interested, the cause of the downtime issues we suffered over the last week have been reported by The New York Times
as the biggest DDoS attack in history.
The reason it was an issue for us: We use CloudFlare. Spamhaus were the target. They couldn't handle the attacks on their own so they used CloudFlare for protection. The attackers couldn't take down CloudFlare so instead they attacked their network providers. One of the providers was the London Internet Exchange. And that meant some of you who were routing through that exchange, and other targeted exchanges, couldn't get through to MW during the attacks.