Some wise owl once observed: "Your victories can land up costing you more than your defeats." It seems churlish, on the back of his comprehensive and surprising victory last Thursday, to sound this note about David Cameron.The British prime minister and his Conservative Party defied the pollsters by winning an outright victory in the hard-fought UK election.He also upended recent electoral history everywhere, in the teeth of a great economic recession, by actually adding seats to the governing party's numbers and by immolating his coalition partner, the Liberal Democrats, in the process.Now that Cameron and the Conservatives have a slender outright majority, he will soon enough face some internal challenges on the very subject that capsized the last outright Conservative election winner, John Major.Major had a larger majority than Cameron but endless internal party conflicts over Europe sapped his government and, in the end, he governed with no majority at all. This was a prelude to being swept out of office by Tony Blair's resurgent Labour Party in 1997.Cameron's promise of a referendum on Britain's continued membership of the EU stilled for a while the nationalist impulse in his own ranks. But once the campaign on whether his country should stay in or leave the EU starts, rest assured the sleeping dragon of nationalism will revive.The price of Conservative victory, pitting the English heartland against the danger of the Scottish nationalists, worked its magic in Middle England. But the almost clean sweep the Scottish nationalists achieved will come with some hefty price tags.Nicola Sturgeon's party so overwhelmed the Labour Party that poor Ed Miliband's crowd landed up 100 seats behind and cost the leader his job.Cameron, having used the politics of fear about Scotland so well in the election, might find himself in a few years presiding over the disintegration of the UK, which is so dear to his heart.On the subject of nationalism, I was called on at the weekend, at the elective congress of the DA, to offer a tribute to its outgoing leader and some thoughts for the new man at the helm.One of the items of advice for him was this: "He must tell the truth: nationalism of whatever stripe divides and excludes and, as history has proved, in the end always fails."The National Party certainly failed, and the ANC currently rides a sea of troubles.My point was that, if you want to build an inclusive country, anchored by a winning economy and at peace with itself and the world, you need to offer a vision and practise politics that have room for everyone, not just the elite beneficiaries of your political programme.The day before my speech and the election of the new leader, one of the very few people still around in this country who can personally remember the infamous nationalist Dr HF Verwoerd spoke. Allister Sparks nearly snatched defeat from Mmusi Maimane's massive victory. At the very least, he netted an epic own goal.I need to note that Sparks, who rose to prominence as editor of the fiercely anti-apartheid Rand Daily Mail, never approved of my leadership of the opposition.After the abysmal performance of the Democratic Party in 1994, which led to my election as party leader, Sparks wrote off the party. In a column in The Star in June that year he wrote with some approval that "one of the more intriguing phenomena of South African politics is the decline and threatened demise of the DP".Attending the DA conference at the weekend, he might have seen that his political obituary, penned more than 20 years ago, proved a mite premature.So I was not surprised that, when Sparks listed a group of impressive and clever politicians he had encountered, my name was omitted.But when a Twitter firestorm devoured him for including HF Verwoerd in his magic circle, I was delighted by the omission.Still, I suppose you should cut Sparks some slack.A former media owner and amateur historian, Conrad Black, wrote of the phenomenon of "the great bad man".History is filled with terrible men who achieved extraordinary, if baleful, things.Back in 1999, when parliament bade farewell to the great Nelson Mandela, I used a similar distinction in categorising political leaders - "the great and the bad" - in which I included Hitler and Stalin (and to which you could add Verwoerd); as opposed to the "great and the good", in which I included Roosevelt and Churchill.I suggested that Mandela occupied an even rarer perch: "Also of the good, but a leader born with a special grace that transcends the politics of his age."Sparks's lack of such a qualification did him in, but unintentionally he provided a very useful lesson to the newly elected Maimane.However good and well-intentioned a leader you are, your leadership will often be defined by how quickly you douse the fires started by others, which you never saw coming.So, to the advice already offered him, I would add: "Learn to be a good fireman."..