Westminster Hall is the oldest building in Parliament.

It's a fragment of the ancient Palace of Westminster, which has survived fire, blitz and new building.

It's a huge stone hall with a magnificent wooden ceiling, and it's also a reminder that Parliament is a place where history is made.

In the 900 years since Westminster Hall was built, it's seen many momentous events, but none as dramatic

as one that took place over a few days in January 1649.

In that cold month, after many years of bloody civil war, a triumphant parliament put on trial

a captive king for his life. That king was Charles Stewart, Charles I, King of England, Scotland and Ireland. I'm with

Dr Stephen Roberts of the History of Parliament Trust who can tell us more about the events

surrounding the trial of the king for high treason, and then we're going to see a really

remarkable document in the parliamentary archives that brings that history to life. Stephen, how

did it come about that a king was put on trial by his subjects?

After the first civil war of 1642 to 46,

an uneasy compromise was reached between the Parliament and the king and other factions.

But in 1648, conflict broke out again,

much to the anger of the army and those who had opposed the king during the first civil

war. So the trial of Charles I really was born out of exasperation. It was determined that

some permanent outcome to the conflict should be achieved. How did the king approach the trial

for a king to be tried by his subjects, that's probably the first time

in British history that that's happened?

It's clear from the beginning of the trial that Charles I didn't take the proceedings

seriously at all and that he, from the outset, questioned the authority of Parliament to put him

on trial and of course he had the law on his side for that, and it's clear throughout that Charles I was defiant and rather contemptuous of those putting him on trial and of course he had the law on his side for that and it's clear throughout that Charles I was defiant and rather contemptuous of those putting him on trial and only towards

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