My welcome as well, Grace. Hope you decide to stick around.
No doubt the trend toward hyphenated names in the US is a product of our growing sensitivity to gender equality. After all, if a married woman decides to keep her maiden/birth [choose one] name, why shouldn't her children get to keep both names? The obvious flaw in this practice arises when offspring from two such families marry. Will their kids be saddled with four names and three hyphens?
I get the idea that the double-name situation in the UK is altogether different. I'll welcome a correction from one of our friends from the mother country, but it's my guess that sometime in the past two prominent families, joined by marriage, felt the need to seal the bond with a double-barreled moniker. The Prince of Wales's girlfriend has one of these names, and I've noticed references to yound Prince William being linked with a number of young women with similar tags. To the American ear (at least to this pair) these hyphens suggest just a dash of elegance. But then let's not forget Mandy Rice-Davies. Colorful, but not exactly elegant.
