Just an observation, but I've found the expectations of what constitutes a close cyclist-cyclist overtake depends a lot on the local cycling culture. For example, I was surprised how close other cyclists would pass (or how little room I was given to pass) on Dutch feitpads. I think London is going the same way; as numbers increase there's less room per cyclist, but also a greater expectation and acceptance of closer riding.
Quite possible that Londoners have different expectations about personal space from we West Country folk, but now that I have looked at it several times I increasingly see the lady cyclist as the real source of the problem. The driver seems to slow down to almost the speed of the cyclists, and assess the situation before moving forward, I would not be impressed with the distance he leaves but it is not too unusual. I think he can be accused of misjudgement and of not understanding the distance that should be allowed. You will note the fact that he could have gone further over to the right, but chose to bisect the space between cyclist and right hand lane boundary, which is almost the norm, and ought to be worked on.
The cyclists generally seem to be treating the road with sort of exuberant attitude that motorists no doubt adopted about 1905. If we see motorists doing that today we justifiably condemn them. Things have become much more organised and roads are not racetracks, but transport systems where vehicles basically follow each other, and that applies to bicycles too.
In this case the road is plainly marked in lanes and vehicles should be using one or the other, not straddling the lane boundary like the lady cyclist, and while overtaking too.