I'm completely surprised at bar people on here never having heard it before! I've often ordered a lemonade and lime over the past 30 years and have never had so much as a look of confusion!!
The issue is that she didn't call it a lemonade and lime.
She called it a lemon and lime. It's far more ambiguous than lemonade and lime.
It could be;
Lemonade and Lime Cordial
Lemonade and a slice of Lime
Bitter Lemon and Lime Cordial
Bitter Lemon and a slice of Lime
Sparkling or still water with a slice of Lemon and Lime
7up (brand name of a Lemon and Lime Pop)
A literal lemon and a lime (which my autistic parent genuinely would have handed her without so much as blinking!)
Lemonade and Lime Cordial are totally normal as a drink here in Lancashire too. It's obvious what you're asking for put like that. I've never heard of "a lemon and lime" and can understand why a bar person would need to get have some clarification.
Maybe, but surely if you knew what 'lemonade and lime' meant, you'd realise what they meant by 'lemon and lime'? Or perhaps not...
I really don't think so. There's a lot of room for error. Even with Lemonade and Lime, I'd ask "Lime Cordial or a Slice of Lime?" cos lets face it...what's "Coke and Lime", or "Lemonade and Orange"? Could be Coke with a slice of lime or orange squash and lemonade or fresh orange and lemonade.
My friend was a barmaid here in the North and was bemused on our London trip to be served half a lager and half a guinness in a pub near Tower Bridge when she asked for a Lager and Black! We laughed a lot but could see how the bar man guessed what she meant and arrived at the wrong conclusion.
People should just ask for exactly what they want.