Christopher, Ian, Peter and David aren't 1940s/50s names. All were popular until the 80s, David probably until the 90s (I know a few 90s Davids), Christopher (Chris) was still popular when my DC were born (late 90s, early noughties) then faded away for a bit but is popular again as Christopher (Kit).
I think there is a different "cycle" for classic names and non-classic names.
I think the 70s/80s classic girls names are the next classic names to come into fashion - Louise (top 10 in France), Helen, Sarah, Rachel, Susan/Suzanne/Susannah, Rebecca, Julia, Caroline. Maybe Andrew, Matthew, Jonathan/Jonathon, David, Richard, Mark, Paul, Adam, Stephen, Robert, Simon for boys. I think the next era of non classic, "fashionable" names to come back is from the 50s/60s eg Linda, Carol, Patricia, Nicola, Clare, Howard, Douglas, Clive etc
I also have a theory that the ironic human names 20 somethings give their pets are the next generation's cool names. At least, everyone I knew when I was 20 something had pets with granny/grandad names like Wilf, Fred, Bertie, Alfie, Archie, George, Elsie, Agnes, Maisie, Edith, Mabel. Which, based on the names of all the hipster pets wandering around East London about 10 years ago, means Barry, Gary, Sharon and Tracy are coming back very soon!