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I have been in a slightly similar situation but we went in through the doors on each side. The two of us were wearing all the bells and whistles but neither of us were pointing guns and we got the guy out of the car with collateral damage of three cars. But we had no info on weapons only that the vehicle had been driven at officers closing the road for a Windsor guard change. It wasn't dark and there was only two of us so our thought processes were different, we could have escalated if necessary but didn't. Sgt Blake and his people were at the sharp end straight away with no time to plan and the suspicion of a firearm, possibly. With the car being driven at them raising suspicions too. Then it's "me or him" and we know the result.
I am no fan of plod, nor am I racist. It has been accepted that the police are racist. However, in this particular case perhaps the racism angle could be ignored based on the evidence.
We have a resident expert on armed police procedure, @Constable_Savage, who even took his forum name from a sketch about a racist cop. I would value his opinion.
Just as a thought, had this been been the US of A, every cop present would probably have emptied their magazine.