Its a really interesting, complex, discussion, but the class thing is played on too much. Outside of London (which resembles hunger games these days) class is a matter of how you present yourself. Go to Yorkshire and everyone from the landowner to the builder is happy to shop in the same places. I found more of a class divide in the US than I did back home
The British respect and admire hard manual work. A labourer isn't looked down upon by someone who is wealthy (a British wealthy person anyway) and some of the most affluent people are landowning farmers.
We as a people have that wanderlust and class doesn't really come into it. The Scottish made up a substantial amount of those who moved out to the empire. You could argue that its Norse DNA, but that doesn't account for the Irish diaspora. I think it's more that we are a sea faring nation and have that exploring nature hard baked into us.