Months before his execution, King Charles I was planning to build new Houses of Parliament to placate his critics, according to new research.
Architectural plans drawn up in 1648 by his court architect, John Webb, have revealed magnificent designs for a House of Lords, a House of Commons and their lobbies alongside private royal apartments.
The plans were thought to be designs for a royal residence when they appeared in an obscure 1942 book as drawings by Webb, an assistant to architect Inigo Jones.
Their true significance has now been discovered by Dr Simon Thurley, a leading historian of English architecture, who was chief executive of English Heritage and curator of Historic Royal Palaces.
The complex was so vast that it would have been one of Europe's largest royal buildings.
What makes the scheme all the more extraordinary is that it reveals the thoughts of the king as he contemplated a future that was never to be.
Soon afterwards, on January 30, 1649, he was beheaded as a traitor and public enemy on January 30 1649, following a civil war sparked by his authoritarian rule and quarrels with Parliament.
On his release from house arrest in Carisbrook Castle on the Isle of Wight, he made a last-ditch attempt to save his kingdom and his life, presenting architectural plans for a palace that put Parliament, rather than the monarch or the church, at its centre.
Months before his execution, King Charles I was planning to build new Houses of Parliament to placate his critics, according to new research
Architectural plans (above) drawn up in 1648 by his court architect, John Webb, have revealed magnificent designs for a House of Lords, a House of Commons and their lobbies alongside private royal apartments
He hoped it would show his critics that he would reign differently in future.
Dr Thurley said: 'The excitement then was that they had actually worked out who the plans were by.
'They obviously show a whacking great palace but, bizarrely, nobody asked, "what is this complex of buildings in the centre?"
'The excitement now is we actually know what they were for and it opens an extraordinary shaft of light into the mind of this tortured king, who is at his wit's end.
The plans were thought to be designs for a royal residence when they appeared in an obscure 1942 book as drawings by Webb, an assistant to architect Inigo Jones
Their true significance has now been discovered by Dr Simon Thurley, a leading historian of English architecture, who was chief executive of English Heritage and curator of Historic Royal Palaces
'He's throwing the last dice on the table. Everybody thinks it's going to work. Then there's a military coup. The moderates are kicked out of Parliament and they chop his head off…
'No-one has ever suggested at any point that this plan is anything to do with Parliament.
'Everyone has assumed that this is all about royal accommodation.
'No-one has ever spotted that you've got this incredible plan where you balance the House of Commons and House of Lords across a big lobby, connected directly with the royal palace, much as it is in the 19th-century Palace of Westminster today.'
The new Houses of Parliament were not built until the reign of Queen Victoria. Above: They are depicted above in 1900
He added: 'If you look at the geometry of the plan, the thing that is right in the centre of the palace isn't the king's throne-room, his council chamber or a chapel.
'It's Parliament. That's a really big surprise.
'When you think that the new Houses of Parliament wasn't built until Queen Victoria's reign, this is the most ambitious attempt to
