Iain Duncan Smith is a former Secretary of State for Work and Pensions, founded the Centre for Social Justice, and is MP for Chingford and Woodford Green.

It’s scarcely a week since the surprise announcement of a general election, and some two weeks before the formal start of the contest, but already the Conservative manifesto is centre stage in interviews and articles. It is natural that it should be – for although a strong majority in Parliament will help the passage of the Great Repeal Bill, and assist negotiations in Europe, an enormous part of the reason for this election is to give the Prime Minister a full mandate for the changes she wishes to make in domestic policy.

To achieve this outcome in a controlled way is the job of the manifesto. Yet these are never plain sailing – even in a fully planned and anticipated election. You only have to recall the 2015 pledge not to raise income tax or National Insurance Contributions to understand that. Recent pre-manifesto commitments, such as the decision to keep the 0.7 per cent foreign aid target, and retain the pledge to cut migration to the tens of thousands, may not have been planned quite that way – but, whilst unexpected so early, I fully understand why the Prime Minister felt the need to make such commitments now.

I am no fan of the cash target for overseas aid, preferring to focus on life changing outcomes instead. But, as with the immigration target, both announcements shut down unhelpful speculation, and start to define the balance of who the Conservatives are. A reputation for strong migration control will be well balanced by the compassion to help others less fortunate than ourselves abroad.

Yet disagreements in the upper echelons of government about elements of what the manifesto might contain once published should be of more concern, and will be seized on gleefully to show a level of disarray. This will makes good journalistic copy for now and, though to some extent a temporary lack of clarity is to be expected, since the snap poll decision meant that the Party has to complete a policy process in two weeks or so. However, we need to be wary that disagreement doesn’t become the underlying narrative, particularly if the most critical part of our narrative is strong and stable leadership.

The real issue for me is not who disagrees with whom before the manifesto is published, but what kind of manifesto would best suit a Theresa May-led government. From grammar schools to pensions, it is hard for a Prime Minister who wasn’t voted into his or her position to justify changes when they may be different from those of their predecessor. This is particularly the case here. The 2015 manifesto was enormously detailed, and contained within it political devices aimed at trapping the opposition. Whether the one in question was the welfare cap or the tax pledge, these were not designed to add value to the job of governing, but simply to box the opposition in.

So we face an early choice. Do we go for a fully prescriptive and detailed list of all the things we want to do and won’t do, as was the case in the 2015 manifesto, or do we use this as an opportunity to set out the key values and principles of the next Conservative government?

I feel we have gone too far in publishing detailed and overly political manifestos which make it difficult to govern subsequently. On re-reading Margaret Thatcher’s 1979 manifesto, one is immediately struck by how well written it is. The narrative style makes it easy to get a sense of the core values of a future Conservative government and these, in turn, are illustrated by key policy proposals – not always detailed – which focus the mind on how the principles that inspire them will be applied.

Take, for example, the principle of a property-owning democracy. Here sits the iconic home ownership commitment, “…In the first session of the next Parliament we shall therefore give council and new town tenants the legal right to buy their homes…….” This was perhaps the key policy that came to define what a Thatcher government stood for: giving ordinary families who strive, but who were previously unable to get an opportunity to improve the quality of their lives, a real chance of improvement.

If we return to the present, Theresa May first set out her plan as the next Prime Minister on the steps of Downing Street. So we must find a way through the coming manifesto essentially of convincing a sceptical public that the Conservatives are on their side, and will deliver real life improvement.

Of course it will be necessary to outline some detail in some areas – in order to affect the relationship with the Lords, and the application of the Salisbury Convention to, for example, Brexit legislation. However, such forms of words will not be aimed at the public as a whole: indeed, hardly anyone outside of the media and politicians reads manifestos.  None the less, the coming one will need a key defining element which evocatively describes the next administration’s purpose: not so much who or what we are against, but what and who we are for.

Of course negative campaigning helps to win elections. But in this contest, Jeremy Corbyn already makes the coming outcome evident in a way that I haven’t seen since Michael Foot. Polling shows that the mere mention of his name ensures that Labour supporters doubt their allegiance. That is why our core message of strong and stable leadership versus a coalition of chaos needs to be be complemented by a manifesto that is optimistic about Brtiain’s future – and restates our belief that, despite all the Jeremiahs and their warnings of impending doom, a Conservative Government underpinned by its values of personal responsibility, free markets, individual liberty, enterprise and stable family life will offer real hope for the British people.