Yesterday I got mocked for calling my secondary school "high school".

Using DfE data I can prove that I'm not weird - I'm just from the North West.

Does anyone know why usage of "High School" in school names is so localised?

@jonty it depends if the area's local education authority at the time arranged the education under their remit into primary school, middle school and high school or not.
Mine did not. Straight from leaving primary, at the age of 11,into the same secondary school until I left for an undergraduate degree at the age of 18.
@jonty mind you, all the secondary schools in that town have recently merged and rebranded as <town> High School, but still serves ages 11-18
@zymurgic @jonty yep, my dad said traditionally Tory councils divided it into First, Middle and High schools while Labour councils did Primary and Secondary schools