With the spread of American popular culture (movies, books, franchises, etc.) and technical jargon (manuals, Web syntaxes, default spell-check settings, etc.), I'm wondering if there have been any studies on a resulting general change in the use of traditional British English conventions, particularly in places such as Britain and Ireland, in the direction of American conventions.
In particular, I'm looking for the results of systematic studies on the topic, or strong evidence for change or lack of change of British English usage. (For example, the change of a few key conventions over the past 5, 10 or 20 years.)
I refer equally to spoken conventions (e.g., "come and see" vs. "come see") as well as spelling (e.g., "centred" vs. "centered").