What was most important was doubtless having the perfect Oxbridge background & being an accountant. Being lesbian and indeed being a woman certainly ticked the diversity boxes all of which lead to her being fast tracked. Why would the Menezes incident get in the way of her rise to the top? All it proved to her superiors was that she was also willing to make the call to have someone executed on the precautionary principle: that she had the " right stuff".But of course I've said this and you have chosen to reduce what I actually said to " she's a lesbian appealing to the middle class" so you can then describe it as a " weak explaination" which then leaves a mystery to be solved.
Menezes has been identified as a threat merely because he was a young adult male believed to have come from the address they were targeting. Mr Stanley was murdered because one member of the public misidentified a table leg as a gun and a Scottish accent as an Irish one. As the rules stand it doesn't take much at all to be labelled a potential "threat" and treated with lethal force. I have little doubt that if I had merely walked to my equipment and hadn't instead spotted them and came out with my hands on the air I wouldn't be here to write this because my acoustic set up was for obvious reasons near a major railway line and could with a little imagination be taken to resemble a missile launcher. As no police shooter ever gets done for murder that's exactly what happens when you tool them up: there's no mystery about that either.