So whether the PM did or did not attend is a good indicator if he did that plate-stepping.

Maybe maybe not. But Not enough data to judge either way. It is also important to note the meeting may have been charged to present the PM with reasoned options.As was said earlier it is not essential for the PM to be present. The meeting was in cabinet office briefing room A. We have no knowledge of the frequency of meetings, the subjects discussed, or the constituent members.
The only gaugefor comparison we have in the public domain, that I can find, is that Blair attended 3 cobra meetings in the fist five years of his premiership. Apparently it is a big deal Boris missed a couple of meeting over the space of 2 months. Without knowing the members, or matters up for discussion it is merely a smear from the left. More "window" thrown out to needlessly distract the government from their job, while they have to refute the more outlandish media distortions. I would have thought the left would be better served seeking unity than constantly sniping at thee government, because once those court cases start labour is going to be a busted flush - straight down the pan.