But that's more because they want to keep the charter, no? I mean that keeping the UK constitution "living" is much easier since the written parts can be legally changed easily.
And the 2 party system is a result of US electoral and constitutional law, which is entrenched. If the US had a new constitution from scratch today I don't think it would feature the electoral college, it's there because of legal inertia.
Yes, but I'm not arguing the US Constitution is older than the UK one, although it is much older than that of almost all countries I think. I'm arguing that the UK doesn't suffer from having an old constitution because its constitution changes more easily than the US one.