I grew up abroad and did Latin and classical Greek at school. I would love to set up a Latin GCSE at my school (I currently teach English at KS 3 and 4 and sociology at KS 5). I've had a look at the OCR Latin paper, and I'm fairly confident I could teach it if I brushed up on my grammar and vocabulary. I haven't discussed my ideas with anyone in school yet, but I know there would be interest among the pupils and have a feeling the head would love the idea (school has a relatively deprived catchment and the head is keen to shake off its historically bad reputation).
I'd love to hear more from people who have experience of teaching it, or work in a school that has it on the curriculum, especially if it's not in the private sector.