US vs. UK: What's Going On Here?

This thought has been brewing for awhile, but since I find triumphalism—and even gloating—rather loathsome, I have kept it out of these pages.  Until now.

The thought is:  US-based firms have out-maneuvered their UK-based counterparts in staking out a serious presence on the other guys' home turf.  To be precise, the footprint of US-based firms in London specifically and Europe generally is far vaster than the footprint of UK-based in New York specifically and the domestic US generally.

To discerning observers of the market, this is not news; it only becomes news when a pithy article sums up the frustrations of the Magic Circle and contrasts it with the recent coup of Milbank on their home turf.

So there: We've said it.  Now to the far more interesting questions:

• Q.:  Are there systemic differences in how US- and UK-based firms approach overseas expansion.  A.:  There must be (tautologically said).
• Q.:  Are those differences cultural, financial, or both?  A.:  Almost to a certainty, both (still in the realm of the tautological).
• Q.:  How can we describe, and what accounts for the origin of, those differences?  A.:  Now it's getting interesting; stay tuned.