The best laid plans of mice and men…Reshuffles are a fascinating game of 3-D chess. Something like 25 Departments, probably about 120 Ministers, PPSs and Whips all told out of 365 Tory MPs. 108 of them are brand new, so will not be given ministerial roles, although they may become those unpaid Parliamentary bag-carriers, Parliamentary Private Secretaries. Leaving aside others like me who have independent Parliamentary careers in select committees, their constituencies and so on, the talent pool available to the PM is surprisingly limited, despite the large Tory majority.

Throw into that mix some ambition to change the machinery of Government itself by amalgamating or abolishing departments here or there; add in personal spats and animosities; chuck in deflated egos, disappointed high risers, and the bad, the mad and the dangerous to know, and reshuffles are always tricky operations.

The PM was determined to create a Government of all the talents. He wanted to bring on some overshadowed talent from the lower ranks, clear out a bit of deadwood at the top. He wanted to reduce the number of people attending Cabinet without being a member of it, and he wanted some moderate degree of change in Government departments. This Reshuffle - which is not yet complete at the moment of writing - has achieved much of that.

Yet at the heart of it is the age-old power battle between No 10 and No 11. The Prime Minister - who is, after all, First Lord of the Treasury- wants to get on with doing things, all of which cost money. The Chancellor, quite properly, needs to balance the Nation’s books. That is a struggle which will always lie at the heart of Government. (Blair vs Brown; Cameron vs Osborne.) So the PM sought to exert his control via the network of Special Advisers; Sajid Javid saw the reduction in the power of the Treasury which that would mean, and concluded that he was becoming ‘Chancellor in name only’ and so could do nothing other than resign. And a resignation at that level in the middle of an already complex reshuffle throws the whole pack of cards up in the air. One resignation or refusal of a job makes the whole row of dominoes fall over.

The complex chess game is played out on a big board, the ministerial appointments listed down one side, with yellow post-its representing the available MPs being moved back and forth. On at least one occasion a candidate was overlooked because his post-it had inadvertently fallen on the floor. On another, my friend Brian Donohoe was offered a job by the PM, mistaking him for someone else called Donohue. And Tim Yeo missed out altogether when the Golf Club Secretary caught up with him at the ninth tee to say that No 10 was on the phone. A sceptical Yeo played on, only to discover to his horror when he made it back to the Club House that it had indeed been the boss, and that in the meantime his job had gone to someone else!

I welcome most of the appointments and changes the PM has made. The mix constantly needs to be refreshed, young blood needs bringing to the top. But the Chancellor’s resignation shows what a nightmare a big reshuffle such as this can become. No-one who has ever had to make anyone redundant, or sack them, can envy the PM this aspect of his job. Let’s hope the rest of it (junior ranks and Whips Office) goes more according to plan.