I wonder how much Christopher Lukkart-Mummary costs per hour? £300-500 maybe? Still I don't think he will save Archway. You'd need a circa £1000 to £5000 per hour top top QC and even then is there a case?
It has to be a serious issue that derails a CPO. And if CLM QC is simply saying: adding 5k seats, a gym and a few more houses makes the project somehow less viable, then they are really desperate.
Just to be a QC is impressive enough, I don't think there is necessarily a huge different between their skill levels once you reach that high.