I've noticed that the girls are younger in all the adventure books - Jo is a few years older than Fanny in the Faraway Tree, with Bessie in between. Bets in the Find-Outers is eight, Pip, Daisy and Fatty about 11, Larry is older at 12 or 13. FF as above but the same ages for Jack, Philip, Dinah and Lucy-Ann (x of Adventure), Jack, Mike, Peggy and Nora (Secret Island), the Adventurous Four, etc.
Subconscious justification?
It's probably relevant that I read the books in the 70s so corporal punishment was still the norm in schools and far from unusual at home, but also the most problematic books had gone out of print - I'd never heard of the Three Golliwogs until I was an adult, for example. The only gollies mentioned were invariably the mayors, in Toytown (Noddy) and in the Land of Toys, so most respectable. The baddies tended to be goblins (greenish), nouveau riches, or vaguely-Nazi types so yes, foreign, and often swarthy with it, but the good-hearted jolly foreigners were equally numerous.
Some of the Blytons I won't share with dd until she's old enough to understand subtext properly - the Put-em-Rights and the Six Bad Boys - the latter is hugely progressive for its time, trying to show how a group of diverse boys ended up in juvenile Court, and does show how their situations were all regarded by institutions and locals of the day. Hugely educational while also viciously anti-Irish and nasty about women who worked but didn't have to. Island of Adventure is I think the only other one that is beyond the standards I'm willing to explain, though if for example I still had my copy of Little Black Sambo (not Blyton) I wouldn't show it to the kids until they're much older. Five go to Smugglers Top has the baddie pretending to be deaf, so that will need talking through so dd doesn't think that's plausible let alone likely.