Gordon Brown has �lost Scotland� and is putting the United Kingdom at risk, David Cameron asserted yesterday in the wake of the row over Wendy Alexander.

Gordon Brown has "lost Scotland" and is putting the United Kingdom at risk, David Cameron asserted yesterday in the wake of the row over Wendy Alexander and her call for an early referendum on independence.

At a lunch with Westminster journalists, the Conservative leader spoke about his astonishment of the events last week when Ms Alexander, leader of Labour in the Scottish Parliament, made her call but was not backed on the specific policy by the Prime Minister, who made clear that the Calman Commission - looking at the powers of the Scottish Parliament - should report first.

Mr Cameron said: "It's extraordinary. The one thing I thought about Gordon Brown was that he really understood Scottish Labour, he really understood Scotland and he really cared about the Union. He's now lost Scotland, is losing the Scottish Labour Party and is putting the Union at risk. It's an extraordinary set of circumstances."

The Tory leader also spoke about how he would like to standardise all Westminster parliamentary constituencies, making them all the same size in terms of how many voters they had.

He said: "The one reform I would really like to make is I would like to see constituencies of an equal size right across the country. On the whole, Conservative seats are bigger than Labour seats (which) is unfair. I would like to see a simple system: the same vote, the same value right across the country so that all constituencies are the same size. That would make a big difference."

For Scotland, while such a move would not reduce the number of its MPs - currently 59 - it could lead to some seats, which have sparse populations in the west and north of the country like Na h-Eileanan an Iar, being cobbled together with other rural seats.

Elsewhere in his answers to journalists, Mr Cameron made clear he felt his party was now winning the "great battle of ideas" against Labour.

While he stressed he was not complacent, he made clear these were "exciting" times for the Tories, who had been buoyed by the results of May 1 in England, Wales and in the London mayoral contest.

"You win an election when people genuinely sense the tide of ideas is flowing in your favour.

"We are beginning to win the great battle of ideas in the way the Conservatives won it at the end of the 1970s. That is why I hope that when it comes to 2010 or whenever it is, we will be able to say not just that we won the election but that we deserved to win it," he said.

Stressing that he wanted the Conservative party to be "properly prepared for government" with well worked-out ideas, Mr Cameron went on: "I do not want the Conservative party to think it can slide to victory on the back of an unpopular and unsuccessful government. I do not want the next Conservative party to be a sort of brief interlude while Labour gets its act together.

"I have ambitions and passions every bit as clear as Margaret Thatcher did in wanting to mend Britain's economy in what I would like the next Conservative government to do in terms of mending Britain's broken society," he added.

The Conservative leader dismissed charges that he lacked substance and had no policies. He told journalists that he had clear ideas on welfare, education and strengthening families but would not be bullied into unveiling a budget "in anyone else's timetable other than my own".

He insisted: "We are seeing a Conservative party that is setting the agenda," adding that his party would use "Conservative means" to achieve "progressive" ends, echoing a word often used by Mr Brown's predecessor Tony Blair.

Mr Cameron said the problems suffered by the PM were of his own making and claimed they showed how Mr Brown believed politics was all about "calculation" and finding the dividing line.

He also dismissed Labour attacks against "Tory toffs" on the stump in the Crewe and Nantwich by-election, branding them backward-looking and divisive.

The Tory leader was in the Cheshire constituency on Monday and is expected to go there at least twice more before polling day.