ANDREW Marr has questioned the tactics of both the pro and anti-independence camps and predicted the outcome of next year's referendum could be closer than many outside Scotland think.

The broadcaster suggested the No campaign could be making a "mistake" by "playing the fear card" highlighting the potentially-negative consequences of leaving the UK.

However, he also suggested the nationalists could do more to set out their vision for the future, adding "so far we have heard surprisingly little about exactly how an independent Scotland would differ from a Scotland inside the UK".

The former BBC political editor, who suffered a serious stroke earlier this year, has updated his 1992 book The Battle for Scotland.

In an extract from the new introduction published in the politics magazine Prospect, he writes that "whenever London Scots get together and talk about independence, there is a general assumption the people back home will never actually vote for it - that a vote for the Scottish National Party (SNP) in Holyrood is simply the latest wheeze to put pressure on London for financial favours is blandly repeated in bars and television studios. 'They willnae.' ... I have become less certain: next September, they micht."

When it comes to the attempts by both sides on the independence debate to win over voters, he writes: "Perhaps, by playing the fear card – asking whether an independent Scotland could afford to pay proper pensions, and harping on the size of its share of the UK national debt – unionists are making a mistake.

"The real question, given all the undoubted risks of independence, is whether a separate Scottish state can make enough difference to ordinary life to justify the gamble.

"So far we have heard surprisingly little about exactly how an independent Scotland would differ from a Scotland inside the UK, run by a more congenial centre-left government. Where is the distinctive tax system? Scotland, which used to be known around the world for the brilliance of its education, is these days pretty average: where is the ambitious programme of school and university reform, designed to make Scotland one of the toughest, gold-standard systems in the world?"

But independence would "shake the rest of Britain rather more than we are generally told".

The remaining UK would have "less punch" inside Europe and internationally, and possibly lose its seat on the UN Security Council, he said. He also predicted Trident, on which he said Britain's claim to "world power" status rests, would be dismantled.

Mr Marr is to give a talk on the book at the Edinburgh International Book Festival later this year.

He has made only two television appearances since suffering the stroke earlier this year, but announced at the weekend he intends to return to his Sunday morning politics show full-time in September. In April, Mr Marr made an appearance on the programme, telling viewers he was lucky to be alive. He blamed the stroke on a combination of overwork and a workout on a rowing machine, and revealed he had perspicuously suffered two minor strokes.

l Alex Salmond has faced ridicule after a series of fawning congratulatory letters to sport stars and celebrities was revealed under Freedom of Information laws.

Over a two-year period he wrote eight times to Andy Murray, praising his "near flawless tennis" on one occasion. Others treated to the First Ministerial charm offensive included cyclist Sir Chris Hoy, former Manchester United football manager Sir Alex Ferguson and writer JK Rowling.

Scottish Conservative deputy leader Jackson Carlaw said yesterday: "These unrequited, toe-curling letters reveal just how desperate Alex Salmond is for celebrity approval.

"Thankfully, the majority of these advances were spectacularly snubbed."