Starmer, I think, was holding off on Cooper because she was doing an excellent job gathering information and showing up the government as Chair of the Home Affairs Select Committee.
So she has experience as a minister, experience as Shadow Home Sec and is very informed of current issues, promises, statements and deficiencies.
I've heard it said that a good mantra is to do what the enemy least would like you to do. I imagine Johnson and Patel, who are on a very low approval ratings with Conservative members as it is, are not thrilled by this.
There is a strategy here. Starmer has blunted the Conservatives on anti-semitism and he has distanced himself from Corbyn quite effectively and visibly. So he has addressed the weaknesses that he knew about. Not perfectly and it has come with a price, but it was required.
Behind the scenes the team he was assembling is reckoned to be focussed on talent first and foremost. This is another right step. You need ability and competence. I hope there is no groupthink, but independent thought is encouraged up to the decision being made.
Lastly, there needs to be an overall strategy that everyone understands and can work towards. The main aim, at this point, is getting in to government. Part of the strategy of that is to take down the current one and one way to do that is take out the key individuals.
This I think is why Starmer has been talking to Mandelson. Apart from being one of the triumvirate that got Labour in to power last time, alongside Blair and Brown, Mandelson was on the receiving end of a targeted take down himself.
People talk about Starmer and his personality, but even though it was a different time, Atlee was not known for his charisma. What Atlee, Wilson and Blair were all able to do, was gather and manage a team. They were also strategists. They knew the importance of both. You could say the same for Thatcher. I think you could say the same for Kinnock. You couldn't say that for Major particularly and certainly not for Foot, Howard, IDS, Hague, Miliband, or Corbyn. Cameron understood the importance of these things I think, his failings were elsewhere.
Starmer does understand these things. Talented barristers always have a careful strategy. He knows how to lead a team, as he showed with the CPS and he has shown flexibility when working out how best to influence policing in Northern Ireland.
Whether he has enough other qualities, including charisma, judgement, political and media savvy, remains to be seen.