I described a simple way of testing whether it is true Brown and Blair never missed a Cobra meeting, while simultaneously checking Gove's claim that PMs missing such meetings is normal?
Would you support getting actual factual information about attendance at Cobra, rather than relying on Gove's assertions or other people's memory? If not, I am prepared to rely on the advisor's memory in the absence of anything better.

I would always favour facts over opinions. But Gove was not asserting that the PM was there (which would be the opposite of the The Scotsman claim), but that the PM was not required to be there. The frequency of Brown/Blair attendances does not influence that fact.
From: The Institute for Government
Who sits on COBR?
The composition of any COBR meeting will depend on the situation being discussed. It will be a mixture of officials and agency personnel, alongside ministers, from relevant departments and agencies. The meetings are often chaired by the most senior minister in the room, and the prime minister if he or she is attending, but not always.