Whitehall chiefs Bob Kerslake and Jeremy Heywood split the back-seat driving Like Sir Gus, Sir Jeremy, who has worked in No 10 for a number of years, won the trust of three very different prime ministers: Tony Blair, Gordon Brown, whose chaotic office Sir Jeremy sorted out, and David Cameron. A former Treasury official who took a few years out to work at Morgan Stanley, his charming efficiency wins plaudits from colleagues as well as premiers. "He immediately understands what it is you want and gives you a yes or no," enthused one normally rather cynical insider this week. Others say that, never having run a department himself, he does not understand how much other senior officials have to do. Plenty of mandarins turned up a few weeks ago to help him celebrate his 50th birthday in the newly decorated basement of his home. I am told that, sadly, Sir Bob was in Sheffield that weekend. He used to be the city's chief executive and still has a home there. Sir Bob is the older of the two - he'll be 57 this month. He is also plumper and, unlike the smooth Sir Jeremy, bearded. This week he made his first public appearance without Sir Jeremy, before MPs on the Public Accounts Committee, chaired by Margaret Hodge, the dragon of the committee corridor. She sweetly congratulated him on his appointment, warned him that she'd bite his head off (well, interrupt) if she thought he wasn't answering the question, and repeatedly asked him to speak up - with reason. She seemed to think that, as head of the Civil Service, he could and should answer for all government departments. Whitehall is a federation of them - not a centralised, Soviet-style state. If he's not to be blamed for every last foul-up, Sir Bob needs to find ways of saying this more clearly - and more loudly. Of course, there have been persistent rumours, denied by Sir Jeremy, that our two knights have secret plans to merge the back offices of Whitehall departments, then close entire ministries and concentrate power centrally. Insiders say that they do want to merge back offices and so cut costs and numbers further. It seems, however, that merging entire departments is not on. That would mean putting ministers out of a job - and mandarins never want to upset their political masters. Apparently, Sir Jeremy and Sir Bob do want senior officials to be more explicit with ministers about risk-taking. Civil Service culture has traditionally been to advise against any risks, even when legal challenges are likely. Insiders say there are moves to make politicians and officials - and the rest of us - accept that some risks are worth taking, even when things do not work out well. Meanwhile Bob "n" Jerry are no doubt wrestling with the everyday problems of mandarin folk... Like what to put in the new legislative programme - oh, and how to cope with distracting political crises such as Mr Huhne's resignation. Traditionally, the permanent leaders of Whitehall see it as their job to keep the wheels of good government turning while ministers are off worrying about saving their own necks. Mind you, when ministers are in extremis, Sir Jeremy believes you should try not be too much of a "cold fish." Perhaps he and Sir Bob rehearse a few consoling words during their bilaterals in the car. Hmm? What do they have for breakfast? I can't say. No really, I can't. Yes, there are reports that Sir Bob enjoys kedgeree while Sir Jeremy goes for the full English - egg, bacon, sausage, black pudding, tomato, mushrooms, fried slice and baked beans. But as you know, I don't like to gossip.