I think the answer is what didn't motivate GCHQ to review other distributions. I think you're referring to their End User Devices Security review? https://www.

I think the answer is what didn't motivate GCHQ to review other distributions. I think you're referring to their End User Devices Security review? https://www.gov.uk/government/collections/end-user-devices-security-guidance--2 https://www.gov.uk/government/collections/end-user-devices-s... They didn't single Ubuntu out of a crowd, they just only reviewed Ubuntu which is probably due to the brand name recognition in the government departments the advice was aimed at or possibly the experience of the team doing the review. I have assumed that was what you were referring to and not a different statement?