A century ago, British women still did not have the vote and violent protests by the suffragettes were escalating. Were these women seen at the time as something akin to terrorists, or as activists legitimately fighting for a political cause?

Frustrated by the lack of reform at the start of the 20th Century, hundreds of suffragettes were jailed after taking part in protests.

Until 1912 the campaigning was largely within the law, mainly chaining themselves to railings and disturbing the peace. But activism grew to include planting bombs, smashing shop windows and acts of arson.

Targets were not just buildings, even artworks were mutilated - most notably Velazquez's famous Rokeby Venus, repeatedly slashed with a meat cleaver at the National Gallery in 1914.

There had been earlier concerns. In 1909, the government had been concerned about a plot to assassinate Prime Minister Herbert Asquith. The perceived threat came from an unidentified "little woman" picketing the House of Commons and "wearing a Tam o' Shanter", according to a file only released in 2006 by the National Archives in Kew.

The government's concern was heightened when it was informed that two women had been observed practicing with revolvers at a shooting range.

But the period after 1912 marked a clear escalation.

How suffragettes were described April 1913: Times newspaper - "militant movement of the Women's Social and Political Union…"

June 1914: Home secretary Reginald McKenna - "these women are so foolish and mischievous"

Also McKenna: "What is thought is that the indignity of being sent to Broadmoor as criminal lunatics would bring them to their senses"

In 1913, Emily Davison threw herself in front of the King's horse at the Derby and died from her injuries. Historian Sir Brian Harrison thinks she was probably seeking martyrdom - as later Irish militants did.

"A funeral is a great opportunity for publicity. The militants made the most of the publicity resulting from that death," he says.

But "terrorism" is far too strong a word for the actions of the suffragettes, considering the context, says Baroness Brenda Dean.

"If you look at any major social change, within it somewhere has been a degree of militancy… You've got to throw yourself back to the turn of the century when the whole social order was very different."

Their actions have to be seen through the prism of their inability to use normal means to advocate their views, she suggests.

"These were pretty desperate measures by people in a desperate situation."

Baroness Dean is calling on the government to give a posthumous apology for the way the suffragettes were treated.

Media playback is unsupported on your device Media caption Andrew Marr tells the story of how suffragette Christabel Pankhurst was arrested and imprisoned in 1905

Krista Cowman, a professor of women's studies at the University of Lincoln, says the suffragettes would have been considered terrorists at the time but not in the same way people would view terrorists today.

"The key difference you have to remember, unlike today's terrorist act, where acts are being committed by people who do have a vote, who are enfranchised, these women were completely outside the system but asked to work within it."

It was natural that the establishment would fear the suffragettes.

"Because there were many other political issues at that time, such as the Irish militancy, it makes it more dangerous. If you can't contain your own women, particularly middle class women who have traditionally been a quieter group, then you really are losing a grip on everything," she adds.

Lloyd George's failure My great-great-grandfather David Lloyd George had always supported women getting the vote when in opposition, but didn't make much of it when in power. Votes for women was too difficult to swing and he cared about it less than his welfare reforms - it was a useful Conservative-bashing tool when in opposition but too controversial once he was in power. Dan Snow, presenter, The Lost World of the Suffragettes

However, Prof June Purvis, who wrote a biography of Emmeline Pankhurst, disagrees, and says that there is a great difference between lawlessness and being labelled a terrorist.

Purvis says the Liberal government tortured women by force feeding them when they were on hunger strike and perpetrated other indignities.

"It wasn't just forcible feeding. On Black Friday, 18 November 1910, women were kicked to the ground, punched, their breasts were pinched."

Helen Moyes - who died in 1979 - belonged to the non-militant arm of the suffrage movement, known as the "suffragists". She objected to the militant tactics employed by Christabel Pankhurst, a daughter of the movement's leader Emmeline.

"I saw no value or use of militancy in a cause. I told her that and said 'you use argument and reason in a cause, not militancy'," she told historian Sir Brian Harrison, who interviewed 180 people in the 1970s as part of his research on the suffragette movement.

Key dates for women's suffrage 1867: MP John Stuart Mill supports equality for women in the Second Reform Act, but is defeated

1903: The Women's Social and Political party, later referred to as the suffragettes, holds its first meeting

1918: Representation of the People's Act allows women over 30 to vote

1928: Women over 21 get the vote Listen to women describing their role in the suffrage movement

Independent newspapers, later banned by the government, clever photo journalism and mass protests all brought the cause for women's rights to the public eye.

Dressmaker Elsie Flint, a suffragette who was part of the militant arm, recalled in the 1970s: "People laugh and say what ridiculous things to do, but it was never done for fun. They had to get the notice of the public and that was their way of doing it."

On the afternoon of 1 March 1912 around 150 women were standing in front of shop windows and government offices in London's West End and simultaneously took hammers and stones from their pockets and smashed the windows, explains historian Elizabeth Crawford.

"There was great confusion, they didn't try to run away. They were arrested immediately."

One of the suffragettes, Victoria Lidiard, recalled the attack in the 1970s: "We started at the Marble Arch and... were stationed right down from Marble Arch to Tottenham Court Road - and then bang went all the windows."

An estimated 124 women were arrested. After the window smashing episode, the police used weapons and force to close down the Women's Social and Political Union.

A year later, arson attacks were commonplace. One such attack greatly damaged an unfinished house being built for the Chancellor of the Exchequer, David Lloyd-George, who had become a hate figure for the suffragettes.

Find out more The Lost World of the Suffragettes will be broadcast on Saturday 11 February at 20:00 GMT on BBC Radio 4

Catch up later via the iPlayer The Suffragette-defaced penny Jenni Murray on being a 20th Century woman

Dr Tobias Feakin of the Royal United Services Institute compares the suffragettes to a protest campaign like the Occupy movement against economic inequality, but says today they would not be perceived as terrorists.

"Animal rights activists have used more extreme measures to express themselves, though in the US they do ban a lot of environmental groups as environmental terrorists."

Crawford says she "can't help but sympathise" with the suffragettes, but believes their methods were "a rather dangerous way of going about things".

"We tend to underestimate the amount of damage that was done. At the time they wouldn't have used the term terrorism, but with our experience of terrorism now, if one group is trying to coerce the state, I think we might view it rather differently."