Thousands lined the route of Margaret Thatcher's funeral procession on Wednesday to pay their respects to a prime minister who had a profound impact on Britain, but others turned their backs on her coffin in bitter protest.

The woman who ruled Britain for 11 years has aroused strong passions even in death, but admirers vastly outnumbered protesters along the route as her coffin passed by on its way to St Paul's Cathedral largely accompanied by applause.

Andrew Moodie, 56, a veteran of the 1982 Falklands war, the conflict which for many was a defining moment of Thatcher's time in office, said he wanted to "show respect to a great leader".

"She sorted this country out. She made it great again. She got rid of the unions and supported the forces," he said.

Black-suited young supporters of Thatcher's Conservative Party took up their positions on the route at 7:00 am, three hours before the coffin passed.

"We're here to mark our respect and regard for the greatest peacetime prime minister the country has ever known," said Oliver Cooper, the 26-year-old chairman-elect of Conservative Future, the party's youth wing.

"She gave a huge amount, not just to this country but to others around the world that she helped liberate from totalitarianism. She stood for freedom and democracy," he said.

But others said they had come to show their opposition to a woman whose politics polarise Britain even 23 years after she left power.

Many said it was wrong that at a time of deep public spending cuts, state funds are being used to pay for her ceremonial funeral.

"We're spending £10 million (11.7 million euros, $15.3 million) on it and that's disgraceful and unacceptable at a time of austerity," said 22-year-old anthropology student Casper Winslow, who had the words "society does exist" emblazoned on the back of his t-shirt.

Katie McDonald, a 30-year-old doctor, said: "I grew up in Scotland and Thatcher basically ripped all the industry out of the country. And as a taxpayer I am very angry that I'm having to pay for this."

She added: "I think this is different from going to a party celebrating her death, which sends out the wrong message. I'm still respecting her mourners -- I've come here in black today -- but I'm using my right to make a political point."

Several voices shouted "waste of money" and booed at the funeral cortege.

But the words of protest fell on deaf ears for many of the crowd.

Shaun Cross, 53, a scaffolder, said Thatcher had changed Britain for the better.

"She turned the country around. We were going nowhere fast in the late 1970s. I was working a three-day week, the firemen were on strike, policemen on strike, the dustmen on strike -- the unions had a grip," he said.

"She broke that stranglehold that the unions had and it needed to be done."

And Gary Sturge, wearing the medals he earned serving with British forces in Northern Ireland, said Thatcher was "an exceptional leader of people".

"We'll watch her go past and then we'll probably try to find a drinking hole and have a drink to the old lady," he said.