Actually, it's not double-barrelled names I hate so much as the way they've proliferated over the last 20 years or so with the rise of single mothers and unmarried couples.
Thirty years ago or so, a double-barrelled name was an indication that the person came from the upper crust of society. If you came across someone with a double-barrelled name it was likely to be something like Lord Arbuthnot Tuffington-Smyth or Lady Lucinda Rumpole-Bailey. A generation later and you're more likely to find children with double-barrelled on the playgrounds of the local sink estate than you are on the playing fields of Eton.
When I was a kid there wasn't a single child in my school year with a double-barrelled name. In my youngest son's primary school class there are at least three - possibly more - with many more sprinkled across the rest of the year. Where it was once a sign of a privileged upbringing it is now more likely to be an indicator of an underprivileged child.
I hate it.