Sir Menzies Campbell: You Ask The Questions

Both Labour and the Conservatives have moved away from conventional left and right-wing policies to occupy the traditionally Liberal Democrat-dominated centre ground. Where does this leave the Liberal Democrats? LUKE GODFREY

It puts us in a strong position. The left and right divide in British politics has been replaced by a division between liberalism and authoritarianism. Labour has proven to be the most centralising and authoritarian government in living memory, and the Tories cannot decide where they stand, as shown by their flip-flopping over national identity cards. Only one party in British politics is truly liberal - and that's the Liberal Democrats.

What is the purpose of the Liberal Democrats in the Brown-Cameron era? Is it to outflank Labour on the left or to target Conservative-inclined voters? ADAM DUGUID, Lincoln

It is neither of these things. The purpose of the Liberal Democrats is to campaign for a country that is free, fair and green. These are enduring principles that work to the benefit of everyone. That message strikes a chord across the whole country, which is why we are the challengers to Labour in the North - where the Conservatives have failed to mount a credible challenge - and to the Tories in the South, where Labour has little appeal.

How low would Liberal Democrat support have to fall for you to stand aside? CHARLOTTE COOPER, by email

Liberal Democrats have an important job to do in promoting liberal values in the face of an authoritarian Labour government and a Conservative opposition that is all spin and no substance. These values have never been more important than they are now. I have no intention of standing aside while that job needs to be done.

Will you stand down as leader of the Liberal Democrats after the next general election? ANDREW BELLIS, Newcastle upon Tyne

I have always said that I will lead this party through this parliament, into the election, and into the next parliament. That remains the case.

Should it be Chris Huhne or Nick Clegg who takes over from you? OLLY WILLIAMS, London

There is no vacancy, and therefore no choice to be made.

You always look like you hate Prime Minister's Questions - is it the worst moment of the week for you? JAMES DIXON, Ipswich

Prime Minister's Questions is a pretty tough environment. But it can also be the best moment of the week. When I ask a question about something that's important for individuals and families and it highlights an injustice that needs to be put right, I feel that I have done something that's truly worthwhile.

Why is it that we see so little of the Liberals in the media and why have you been unable to capitalise on your sensible (and popular) policies? MEL NETTLE, by email

I am glad that you hold such a positive view of Liberal Democrat policies: I am sure it won't surprise you to hear that I share it. Unfortunately, the media still tends to present politics in this country as a two-party contest - which it is not. We have to fight for coverage at all levels. I am confident that we will achieve more publicity in the run-up to the general election.

How did you manage to let the Tories steal all your green clothes? And isn't this a real failure of your leadership? STEVE KELLY, Ipswich

I do not accept that the Tories have managed to steal our clothes. For David Cameron, the environment is all about warm words rather than substance. The Conservative Party has no credibility on this issue at all. The Conservative manifesto in Scotland was given a zero out of 10 by Friends of the Earth. They have no proper costed proposals about how to deal with global warming and have a record of voting against important measures (such as the climate change levy). By contrast, the Liberal Democrats have brought forward detailed proposals for green taxes, green homes and green non-nuclear energy. At our party conference in September, we will also unveil a comprehensive set of proposals to ensure that every sector of the economy minimises its contribution to carbon emissions and climate change. We continue to provide real leadership on this issue - not the empty words used by Labour and the Tories. We are ready to take tough decisions necessary on vehicle excise duty and aviation.

Surely the idea of a local income tax is going to be far less popular with your potential voters in the South-east and West than a 50 per cent tax. Didn't you ditch the wrong tax?! JAMES KENYON, Newcastle upon Tyne

Based on the ability to pay, local income tax would be a much fairer system than the council tax, and would benefit millions of people across the United Kingdom, including pensioners and key sector workers. Fairness is a fundamental principle that Liberal Democrats believe should be expressed throughout our tax system. At the moment the poorest earners pay a higher proportion of their income in tax than the richest. We would change that by cutting taxes for those on low and middle incomes who have been badly punished by Gordon Brown's stealth taxes, and his abolition of the 10p tax rate in his last Budget.

Since Gordon Brown is a friend of yours, can we presume you will support him rather than the Tories in the event of a hung parliament? CALLUM ROSS, Edinburgh

No. I don't know if hung parliaments are on Gordon Brown's mind but they certainly aren't on mine. Liberal Democrats are an independent party, which will be fighting for more votes and more seats across the country at the next general election, and aiming to take them from both Labour and the Conservatives. That is our only ambition.

Do you think there's any hope of the G8 achieving anything this week? DAVID SINCLAIR, by email

Expectations for the G8 summit remain high and I hope that participating countries prove able to meet them. So far, the G8 has not lived up to the promises that it made to Africa at the Gleneagles summit in 2005; participating members should take this opportunity to redouble their efforts in that respect. It is also vital for there to be a breakthrough on tackling climate change, which is an increasingly critical issue for the whole of the world and particularly to the millions of people in the developing world who have to bear the brunt of its effects. The Government's laudable commitment to tackle debt and poverty in Africa will be completely undermined unless the G8 countries act decisively to prevent global warming.

If you were to become Prime Minister, which foreign policy issues would you change? KURT WAHLSTROM, Minnesota , USA

Above all I would ensure that Britain 's foreign policy represents Britain's values and Britain 's interests. That means being prepared to rebalance our relationship with the United States, and resume our former and more productive role as America's critical friend. Tony Blair's apparent subservience has been damaging both for Britain and for the USA. Britain must uphold the rule of law. This should be an unbending aim of our foreign policy. Our armed forces must be deployed only where there is just cause, and with the support of both the House of Commons and international law. The folly of the Iraq war would have been avoided if these principles had been followed. Our continued military presence in Iraq is now part of the problem, rather than the solution. We should establish a framework for phased withdrawal.

You have said you support the constitutional monarchy. Why do you think a hereditary public office is acceptable in a 21st-century democracy? GRAHAM SMITH, Brighton

The monarchy is a popular institution, which remains above politics and does not intervene in political decision-making.

I am glad you recovered from your cancer scare. Did it make you reappraise your life? FIONA O'GRADY, Guildford

Thank you for your good wishes. I owe the NHS a great deal. I have been given a second chance and I am going to make sure I make the most of it.

Have you ever tried any illegal drugs? And do you support the legalisation of cannabis, Ecstasy or any other narcotics? WILL SUTTON, Birmingham

I have never tried illegal drugs. The current approach to drug use is not working. It neither deters people from drug use nor ensures rehabilitation and treatment. We need to view drug misuse more as a health issue and focus overstretched criminal justice resources on dealers and organised criminals. The law has to be credible and enforceable. It is important to ensure that we do nothing that would encourage or legitimise the use of drugs.

In the 21st century, can and should a man in his 70s be Prime Minister? FIONA WILKINS, by email

There is no reason why not. Experience, judgement and energy are what is required for public office. Look around you in Britain today, age is increasingly irrelevant.

Did you think it was unfair when people compared you and Vince Cable to Waldorf and Statler, the elderly characters from The Muppet Show? MARTIN FRANKS, Manchester

You need a thick skin in this business. I am encouraged by the popularity of Statler and Waldorf. I only hope that, like them, Vince and myself are regarded as having the best seats in the House.

Were you amused by the late Eric Forth's quip, 'Declare your interest!' when you spoke on pensions reform? ERIC JONES, Bristol

Eric Forth was a friend of mine. We grew up in the same part of Glasgow. He had a reputation for quick wittedness. But the Government's ineptitude in dealing with pensions has left many people very badly off in retirement and created a great deal of anxiety.

How fast do you reckon you could run 100m now? PAUL FOSTER, by email

I have a clear recollection of John Prescott taking part in a photo opportunity by sprinting with young athletes and needing medical treatment! I am still obsessed by sport but don't feel the need to prove it!

Do you regret that Lembit Opik seems to have swapped a political career for a life in showbiz? Do you intend to keep him in your shadow cabinet? ALEXANDER LEITH, by email

The test for whether an MP serves in the shadow cabinet is their effectiveness as a politician, not what they do in their private life. Lembit meets that test. If I did not think so I would have done something about it.

Do you listen to any pop music on your gramophone (or iPod)? If so, which artists? SUZIE MACDONALD, Hackney, east London

I tend to listen to music mainly in the car. My interests are pretty traditional but I meet enough young people to know how important music is to many of them.