By Megan Lane
BBC News Magazine
Four hundred years ago the gunpowder plotters hoped to change the world by blowing up Parliament and killing the king. Had they succeeded, what effect would this have had - and would today's UK be any different?
With 36 barrels of gunpowder stacked directly beneath the King's throne, a group of young, disaffected Catholics planned to attack during the State Opening of Parliament in 1605. But Guy Fawkes, the explosives expert charged with lighting the slow match "therewith... to give fire", was caught just hours beforehand.
Had he succeeded and Westminster been blown sky-high, the country would have been in chaos. The whole of the establishment, including King James I and the aristocracy, would have died in the blast, leaving the conspirators ready to seize the kingdom.
"There would have been a complete power vacuum at the centre of English government; the blast would have killed the king, his direct heir [eldest son Henry], the Privy Council, the law lords, the bishops," says historian Alice Hogge, the presenter of a BBC Timewatch documentary on the plot.
The conspirators planned to kidnap the king's daughter, Princess Elizabeth, from her Warwickshire residence and start an armed rebellion there which would sweep the country. With Elizabeth as puppet queen, a new government would be formed - of whom is not known, as the plotters left no definitive blueprint.
"But Elizabeth was an incredibly feisty girl who swore there was no way she would have worn the crown under those circumstances, so they would have had their work cut out," says Ms Hogge.
Thus the king's younger son, Charles, might have acceded to the throne at four rather than 24. This in itself may have changed the course of history. His personality as a politician was shaped by a difficult relationship with his parents, and his mismanagement and repeated clashes with Parliament culminated in civil war and his execution for treason in 1649.
Historian Ronald Hutton, of Bristol University, says losing his parents would probably have made Charles I a more popular and secure monarch. He would have revered their memory (rather than being determined to ditch his father's policies) and nursed a hatred of Catholicism. "This would have made him much more popular in both England and Scotland than the Anglo-Catholic policies that he adopted instead."
The planned blast would have been powerful enough to destroy Westminster Hall and Abbey; explosives experts believe that Guy Fawkes used 25 times the amount of gunpowder needed to kill those in the chamber above.
The death toll would have extended beyond the great and the good, as Westminster was a ramshackle complex of pubs, houses and brothels sitting cheek-by-jowl with the powers-that-be. Those nearby who escaped death or injury in the blast would probably have perished in the resulting inferno.
"A huge fire would have swept through Westminster, taking out shopkeepers, pub owners and householders," says Ms Hogge.
"It would have caused many deaths and injuries, and widespread damage. Some have suggested it would have looked like Ground Zero after 9/11, it would have had that degree of devastation. That's quite a good analogy."
Such a brutal attack would have fuelled anti-Catholic feeling at a time when those faithful to Rome were already persecuted.
As it was, those planning to kidnap Elizabeth acted as though their plan had worked, telling their friends that James I was dead. Yet they only managed to recruit a handful of supporters, and their small band was hunted down by Protestant vigilantes.
Murder on such a massive scale may also have alienated the Catholic community and any foreign powers that might otherwise have welcomed a Catholic England, says Professor Hutton.
How different might today's UK be if James I's rule had been cut short just two years in?
WHO RULED WHEN
James I ruled from 1603-25
Eldest son Henry died suddenly in 1612
Charles I succeeded throne in 1625, executed 1649
But Cromwell's republic lasted barely a decade, and Charles II became king 1660
"Arguably Great Britain might not have existed as it was James's idea," says Ms Hogge. "He was king of Scotland when he came down to rule after Elizabeth's death. His first parliament was centred on his efforts to try and establish this notion of Great Britain. It was his pet project."
But she doubts the conspirators' hoped-for regime change would have lasted. "You probably would have seen a backlash within 10 or 20 years, maybe even sooner. In the course of history, any time someone took over forcefully, once the dust had settled, you saw attempts to unseat that ruler."
For even in the face of upheaval, society reasserts itself. "A crown with such violence, can it ever prosper? I don't know that it can."
Timewatch - The Gunpowder Plot will be broadcast in the UK on BBC Two on Friday, 4 November at 2100 GMT.