David Cameron seemed a little on edge. We were alone in his study in Number 10, very shortly after the formation of the coalition, and he wanted to ask me something that had clearly been preying on his mind. “This is terribly awkward,” he admitted. “The thing is … George has for so long had his eye on Dorneywood… He’s very close to me… Would you mind if he used Dorneywood instead of you?” He then proposed that I share the foreign secretary’s traditional grace-and-favour countryside retreat, Chevening, rather than Dorneywood, which was ordinarily used by the number two in government.

I was a bit taken aback. I thought he wanted to ask me something important. It hadn’t really occurred to me that I might get a retreat to use at weekends, still less that there was any great distinction between one or the other. Cameron’s plea suggested that George Osborne had been measuring up the curtains for years.

I accepted the new arrangement and found myself sharing Chevening, a grand mansion in the Kent countryside near Sevenoaks, for the next five years with the foreign secretary, first William Hague and later Philip Hammond. Not at the same time, I hasten to add; that would have been taking coalition a little too far.

Whether or not occupying Dorneywood made any difference to anything, I couldn’t say. But, like Westminster itself, many of the so-called trappings of power – grace-and-favour mansions, grand offices, ministerial Jaguars – can seem completely alien to people who have not spent their lives preparing for power. As such, it is easy to underestimate their importance.

When it was suggested that I take an office with no publicly recognisable entrance of its own, I didn’t mind, as I thought I wouldn’t need an equivalent of the Number 10 door at which to receive guests. When it was decided where I would sit in the House of Commons at Prime Minister’s Questions, I thought it made sense to sit supportively next to the PM, to show that the coalition could work smoothly.

Big mistakes. All of them.

***

From the outside, the first day of the coalition government looked just about as smooth a transition of power as you could wish for, but behind closed doors it was anything but. With the negotiations wrapped up in just five days, the prime minister and I spent the morning of Wednesday, 12 May 2010 in Downing Street, appointing ministers to our first cabinet, before sharing the stage in the sun-drenched Rose Garden. When Cameron turned to me shortly afterwards and told me that, “We may have overdone it a bit”, he was probably right. It was easy to get a little carried away with the “new dawn” feel of the occasion. But I soon found out that not only was I physically unprepared for government; government was physically unprepared for me.

It was easy to get a little carried away with the 'new dawn' feel of the occasion

On that first day in Downing Street, there was no office waiting for me. The in-house team at Number 10 quickly switched into gear for the incoming prime minister, but had little idea how to handle a deputy prime minister sharing power at the top. I was ushered upstairs to one of the first-floor state rooms. There I spent several hours, accompanied by Danny Alexander and a small number of my closest advisers, while the civil service buzzed around the building, supporting the new PM and largely ignoring us. There wasn’t even a phone.



While the 200 or so staff in Downing Street leapt into action to support the new prime minister, I was given just a single civil servant. My mistake, at least at first, was to accept the model presented to me. Having negotiated the coalition agreement without the help of civil servants, and with no experience in government myself, I simply didn’t see the need to surround myself with teams of officials. And having witnessed the infantile Whitehall turf war waged by Gordon Brown’s courtiers against Tony Blair, I thought it best to avoid rival power centres.

The most unforgiving consequence was the tsunami of paperwork that fell directly to me to contend with. I was asked my opinion on things I didn’t have the remotest clue about – dense, technical issues to do with the mechanics of everything from local government finance to energy subsidies. Every evening I would plonk myself on the sofa at home with my box and sit there dutifully wading through it, as family life happened around me. I would stay there virtually every night until the early hours. Then I would grab a few hours’ sleep, which were disturbed most nights by our then one-year-old son Miguel, only to get up early to help get our two older boys fed, changed and packed off to school.

The effect was not only physically draining, it was politically debilitating, too. Very quickly it became obvious that the central nervous system of Whitehall lay in the daily negotiations between me and Cameron. At the same time, the two most senior Liberal Democrats in the cabinet, Vince Cable and Chris Huhne, were, notwithstanding their obvious intellectual strengths, not known as nature’s keenest team players. From the outset, their focus was devoted to their own departments – and their own political reputations. While they did this to great effect (and I encouraged them to do so), it meant I was unable to rely on others to defend in the media what we were doing. I soon became such a focal point for anger that I felt the impulse to defend myself publicly. No wonder Osborne said, somewhat smugly, in an interview in 2011 that, having expected to become British politics’ public enemy number one, he “hadn’t reckoned on Nick Clegg”.

I never contacted newspaper editors in response to negative coverage about myself. My only exception to this rule was when my family was affected. Every few weeks, Miriam and I had to devote a fair amount of time and emotional energy to rebutting ludicrous claims: that Miriam was somehow responsible for human-rights abuses in Western Sahara; that she was guilty of tax irregularities in her law firm several years before she was even employed by it; that our decision to send our Catholic children, who had attended a Catholic primary school, to a Catholic secondary school was a sign of hypocrisy. And so on.

I mistakenly assumed that if I worked hard within government, did my homework and took decisions on their merits, then, one way or another, the truth – that the coalition was acting out of reasonable motives – would become plain to see and political dividends would follow. What I did not anticipate was what actually happened: I did all that – and no one knew about it. This enabled critics from the left to lampoon the Liberal Democrats as spineless, and critics from the right to lambast us as illegitimate irritants who shouldn’t have been in government in the first place. The public readily turned away from us. I failed to realise an interesting paradox of modern politics: in an age of unprecedented transparency, the reality of power can still remain obscure to the public.

By the spring of 2011, I was both drained and physically unfit. I smoked several cigarettes a night. I got virtually no exercise. Since becoming leader of the Liberal Democrats, I had dealt with pneumonia, chest pains, a broken toe, chronic coughs and bronchitis, while trying to look perky in public at all times. And throughout all of this, I would regularly crisscross London in the early evening to help put our three young boys to bed before returning to Westminster. No wonder there was a Nick Clegg Looking Sad website. They could have added Nick Clegg looking fat, pale and unhealthy, too.

Over time, I worked out a better balance. I employed a larger team; I took up weekly kickboxing classes and had a rowing machine installed in a cubbyhole near my office; I cut down on the cigarettes and started to eat better. I handled the vast amount of paperwork more effectively by tackling most of it early in the morning instead of late at night, a switch of technique I later discovered Cameron had adopted, too.

I discovered that one of the best ways to master the dysfunctional worlds of Westminster and Whitehall was simply to work outside them as much as possible. I restarted my pre-election habit of holding public question-and-answer sessions. I even started my own call-in show on LBC Radio with the veteran presenter Nick Ferrari. It was condemned as a foolish risk by many in the Westminster village, yet quickly proved to be sufficiently popular that a number of other politicians followed suit.

Much of what I have described might seem like the footling ephemera of political life. But I believe it lifts the lid on something more serious: politics is already populated by a surfeit of political professionals and apparatchiks; if we want people with an independent turn of mind who have led normal lives to represent our country in the future, there will need to be a shift. If every youthful misdemeanour is recycled on social media for ever, if the dysfunctional operation of Whitehall continues to expect too much of people at the top, and if politicians cannot protect their loved ones, we should not be surprised if in future parliament is populated by robots, monks and nuns.

• This is an edited extract from Politics: Between The Extremes, by Nick Clegg, published on 15 September by The Bodley Head at £20. To order a copy for £16.95, go to bookshop.theguardian.com or call 0330 333 6846.