Checking with my peers across the industry I'm in, it is indeed only those with Crowdstrike as their security provider that are affected, and only on their Azure and on-prem Microsoft infrastructure.

Microsoft will get a lot of blame for this, but it doesn't seem to be their fault.

Condolences to all affected by this - which may include my sister and family, who are due to be coming to join us in Portugal from LGW later today