Text to speech: Unable to switch to UK English

My phone (Fairphone) does not have the 'English (UK)' locale, only the US one. I recently discovered how to download custom voices for Google text-to-speech ('Install voice data' from settings) and have downloaded a UK English voice to replace the default American voice, which I find incredibly irritating (sorry, Americans!). Unfortunately, even though I have downloaded the voice data, I still seem unable to switch to the new voice, as 'English (UK)' is still not an option when visiting TTS's 'Language' menu. Am I missing something here? How do I make my phone speak to me in my native language? (My Android version is 4.2.2)