You said on Friday that Gordon Brown was right to say that we cannot walk away from Afghanistan? But how can it possibly be right to stay? David Phillips, Canterbury
We are in Afghanistan as part of a UN-approved international mission. We cannot afford further destabilisation of Pakistan and the region, or the re-emergence of terror groups using a failed state as their base. We need to understand that if we fail in Afghanistan, it will give moral support to jihadists across the world who will conclude that we do not have the moral resolve to see through conflicts, even when we believe that they are in the interests of our national security.
What chance is there of the Karzai government rooting out corruption? Surely it is endemic? Belinda Cormack, Peterborough
Corruption is endemic in the region and to expect a Western-style democracy to develop overnight is naive. The gradual improvement of governance there is something we should definitely seek, but we must be realistic abut the timescales involved.
You've said we may need to be in Afghanistan for many years. But is there a timeframe beyond which even you cannot countenance? And how will we know when we have won the war anyway? Matt Freeman, London, SE5
There is a difference between the military mission and the reconstruction and development mission. Putting a definite timescale on a military mission can only be of comfort to our enemies. The military mission will have succeeded when we have a stable enough Afghanistan, able to maintain its own internal and external security, free from outside interference. We can then withdraw our forces without the fear of creating a security vacuum. The international mission for reconstruction and development will be a much longer- term mission, in line with those in other developing countries.
How can you argue that we are in Afghanistan to preserve national security when the only attacks on UK soil have been home-grown? Derek Jasper, Croydon
There were many British dead in the Twin Tower attacks in New York. We must not pretend that we can isolate ourselves from the effects of global terrorism. It is both disingenuous and irresponsible to do so.
Shouldn't we regard Afghanistan and Pakistan as one and the same problem? Why don't we have UK troops fighting the Taliban in Pakistan? Michael McDonald, Bristol
It's increasingly clear that Pakistan and Afghanistan are the same problem and need to be dealt with as a single policy issue. We are training the Afghan National Army so that it can ultimately deal with the Taliban on its own. The Pakistan army is already able to carry out this task, albeit with some outside help.
Are the Tories a shoo-in for the next election? What challenges do you still face? Peter Maskell, Colchester
Far from it. No party has ever won an election from the position we're coming from after the 2005 general election. We know it'll be a hard fight, but under David Cameron we've got the best possible candidate for prime minister, and we've got the policies Britain needs.
Your leader claims to believe in "progressive ends through conservative means". Is that why he is cutting inheritance tax for millionaires, one of the very few solid tax promises he has made? Tom Morrison, London W9
Inheritance tax is a tax on aspiration which worries millions of families. Our proposals to ensure only millionaires pay inheritance tax are fully funded by ensuring well-off non-doms pay their fair share. We need to move our economy from one based on debt to one based on saving, and this will help to do that. You've got to ask: if Labour think this is such a bad idea, why are they copying it and planning to lift the threshold in April?
After the Kelly Report, is becoming an MP going to be the preserve of the very rich? Frank Barber, Norwich
I sincerely hope not. The Kelly Report will go a long way to restore public trust in politics which is why we've accepted it. Thousands of people from all kinds of backgrounds have applied to become Conservative MPs since our leader, David Cameron, re-opened our candidates list, so there is no shortage of high calibre candidates putting themselves forward to enter Parliament. It is essential that we ensure that politics remains open to people from all backgrounds.
Should Michael Ashcroft pay tax in Britain? Michael O'Toole, London SW20
That's Lord Ashcroft's responsibility.
If the Tories think that our politics (just like our economy and society) are "broken", how do you think breaking a "cast-iron guarantee" on the Lisbon Treaty will help restore trust? Patricia Birley, Wolverhampton
We were betrayed by a Labour government which promised us a referendum and then denied us one. Unfortunately, the Lisbon Treaty is now ratified. Our cast-iron guarantee was that if Lisbon wasn't ratified and if we won the election we'd hold a referendum. Trust in politics has taken a hammering, so we're careful only to promise what we can deliver. Labour's broken promise to hold a referendum must never be repeated, so we want to change the law so that any future treaty that transfers areas of power from Britain to Brussels will by law require a referendum.
What do you feel about the French castigation of David Cameron's policy on Europe? Adrian Cooper, Southampton
I know Pierre Lellouche and understatement is not normally one of his problems. We will be tougher than Labour in standing up for Britain's interests in Europe and occasionally we will get some abuse for it. We can live with that. What would be wrong would be a failure to try to fix the worst parts of the Lisbon Treaty.
Should you return to power next year, won't Europe blight your government just as it did the governments of Margaret Thatcher and John Major? Mary Woolston, London N1
The last Conservative government had big arguments about the euro. We won that argument and that question is now settled. Now the Conservative Party is united in the view that Britain should be an active member of an EU which is an association of nation states but must never be absorbed into a federal Europe. At least in the Conservative party when we have disputes they tend to be on issues of principle, rather than the pettiness of personal ambition and vendettas which seems to have been the hallmark of the Blair and Brown governments.
Which candidate would you support to become the next EU president and why? Jonathan Timmins, London NW6
The job title can be translated from the French as either president or chairman. We didn't think the job should exist at all but since it will, it might as well be something useful. That means not some grand president interfering in Britain's foreign policy but a competent chairman who should help Europe's nations work together. So not Tony Blair. He should be disqualified anyway for breaking his promise of a referendum on whether there'd be a president in the first place. The President of the Council will also need to be good at detail, also not Tony Blair's strongest quality. We'll see who'll come forward, but there are a number of candidates who could do the job.
Could a Tory government re-negotiate powers from Brussels without risking a crisis in our relationship with the EU? Alan Graham, Hebden Bridge
We can. We'll take our time. We'll negotiate firmly, patiently and respectfully, and aim to achieve the return of the powers over the lifetime of a Parliament. Britain brings a lot to the European table. With good will and determination we can achieve our goals.