See, this is your problem, you think freedom or liberty can only be documented, invented, bestowed or taken away, solely by government decrees or contracts. This is why I'm saying our Founders said that we were Created with unalienable rights, which means what government decrees has nothing to do with it. Yes, the barons forced the king to listen to him because he thought he was king and could do anything, but the barons set him straight. It was a bit of struggle, it wasn't done in one day or one document, but we see the struggle, and it continued as it was the fashion of the English personality at that time to understand their God-given rights, (instead of Government-given).
The concept of liberty evolved over time in many strokes towards the goal (which strokes weren't going on elsewhere), it wasn't in just one stroke, though the Magna Carta was a pretty good one. Common law is a democratic way so that no one judge can take the law in his own hands, but must humbly submit and arduously study the opinions of others before him/her, (And this is why I think the Democrats are getting away from this, because they don't review history so much, as they like to find new things in the Constitution to agree with their opining, while the Republicans who respect stare decisis, are necessarily binding themselves to the diktat of Democrat judges, who weren't so humbly following tradition.)
Napoleon did away with common law which had developed in Northern France, and all the mostly northern countries in Europe at that time when he conquered them, making all the law systems more in line with his authoritarianism, and it stands today, none of those countries reverted back to common law.
But apart from so-called Parliamentary supremacy and the legal system (as if civil law were utter tyranny), the only other evidence of this greatness she can come up with is that Britain has not been "occupied" in the last 1000 years.
Britain was the only country that saw Napoleon's defeat whenever they were involved. As far as I know, if the English character wasn't what it was, they would easily have succumbed to Hitler's Air Force superiority, like most Europe had. They were outnumbered something like 1 to 10, but it was the spirit of resistance that kept them steady. It might have been easier just to let it go and think it can't be so bad under Hitler, but liberty isn't always easy, and they chose to fight or die than live under easier conditions albeit tyranny, which is the most horrible idea to them than it is to others that they'd rather take the burden to fight it out.
I talk all the time to Taiwanese who think China dominating them wouldn't affect their lives that much, so as not to be worth fighting and dying for. I think a lot of Europeans thought this way too, and saved many of their own lives by enduring tyranny. That is not the English way, or American, or most other English speakers. We believe in greater things.