To what extent was the La Tene culture caused by migration?

Jan 2015
I've been fascinated by the La Tene culture for a few years now, and something that really intrigues me is where it came from. It's known to have had considerable Etruscan influences, as well as Greek influences (though given that the Etruscans were known to imitate Greek art in some respects, I wonder if the 'Greek' elements within La Tene art can actually be attributed to the Etruscans as well). As I understand it, the general consensus is that these influences spread to Western Europe and Britain by means of cultural transmission. But, I wonder if this could instead be attributed to the movement of peoples. Not necessarily that La Tene Celts were all Etruscans, of course, but at the very least it seems likely to me that a ruling class of Etruscans may have expanded into and dominated Gaul and Britain in about 500 B.C.E. (when La Tene culture appears in the archaeological record in those places).

This would be similar to how the Romans invaded Britain and brought their culture here, though obviously the population were largely still just the native Britons. The fact that the chariots used in the La Tene culture were Etruscan chariots could well indicate that the ruling class were actually Etruscans, the way I see it at least.

Any thoughts on this possibility?