I think it's all about trends, and I very much get what you're saying about 'cheeky chappy' vs more elegant names.
The trend for the past few years has been for nickname-style names, diminutives, etc (especially for boys) and cutesy, frilly, vowel-ending names (I include 'y' in with that) especially for girls.
So Isabella, Amelia, Amelie, Sophie, Sophia, Evie, Ruby, Milly, Molly, Evie, Lily, Olivia, Arabella, etc, etc... Charlie, Alfie, Archie, Billy, Harry, the whole shebang.
But the trend is definitely starting to shift, which is why people on this thread are saying they're noticing more of the names in your original post.
Consonant-ending names for girls are starting to trickle in - Margaret, Agnes, Edith, Mabel. And yes, more formal, less nickname-y names are coming back for boys - Julian, Laurence, etc.
But it takes a while for those on or behind the curve to catch up with those ahead of the curve. People start to hear certain names more and more and they seep into the general subconscious. Suddenly the old connotations associated with the names give way, and they begin to sound fresh and current, and all of a sudden there's a new zeitgeist, and everyone thinks they're bestowing an uncommon, under-used name on their child ... only to discover everyone else is doing the same thing.
There's an eternal debate on MN about the rights and wrongs of putting a formal name on the birth certificate, and using a nickname for everyday. Lots of people feel this is pointless and use the same nn on the BC. This is fine, but without a shadow of a doubt, those names will sound very dated to the next generation. No real harm done and there will be lots of kids (then adults) in the same boat. But those sorts of names will very much sound from this era, by the time everyone has moved onto the more formal sorts of names.
Interesting idea re the political party in power, and whether it's left- or right-leaning. It probably does have some influence, but name trends are far greater than the confines of one country. Most English-speaking countries currently have many of the same sorts of names being popular at the same time, some of which include left-leaning political parties in power.