Where it all began?

I'm figuring it's a mistake, one made based on "Leslie" currently being a 'bi-gender' first name...

--C.K.

I think there are exceptions but isn't it usually Leslie for a boy and Lesley for a girl?

Leslie is a Scottish clan name and there are males and females with that spelling. I suspect that Lesley is an Anglicisation for a girl's name.

Every Leslie I've known (male, female and non-binary) has been a Leslie rather than a Lesley (except for one Lesleigh). This is a very interesting diversion from spanking and I'm gonna look into the name's history now aha. Evening plans sorted!

I always thought Lesley was for a girl, Leslie for a boy. Somewhere I used to work had a lot of donors or trustees or some such, and I remember there was a married couple on the list called Leslie and Lesley. Apparently their mothers had met when they were pregnant and both said they liked a name that would do for a boy or girl.

This is very confusing for us nonnative speakers. My impression is:

Terry is most likely male, and Terri is most likely female,

but

Robyn is most likely female, and Robin is most likely male.

Can somebody please explain the system?

Alef
You are correct about Terry and Robyn but I don't think there is much of a system - you just have to know. I think an 'i' ending would usually indicate female.

Following from your examples, Tony is most likely male, Toni female. Joe is most likely male, Jo female. Danny is most likely male but Dani female. A boy Stephen would be shortened to Steve but a girl Stephanie would be shortened to Steph.

Names ending in 'a' or 'ah' are nearly always female unless they're biblical. Names ending in 'ie' are usually female. Names ending in 'y' is a bit harder as while they are mostly female there are quite a lot of male names or abbreviated male names ending in 'y'.

I always assumed, with examples like this, that the male version came first (often abbreviated from eg Terence or Anthony) and when people daringly chose it for their girls they changed the vowel to indicate the unusual gender. Brief research suggests this is true for Robin/Robyn and maybe Tony/i, but I'm not sure about Terry/i.

There is little or no evidence, however, that such names ever influenced anyone to become a spanko.

TheEnglishMaster
I think that's correct on both points.

Jean in the UK is female but Jean in France is male
Laurence in the UK is male but Laurence in France is female.

Peter in French means to fart
Penny (Penelope) in French is how the word penis is pronounced