Verify transcription performance with UK and non-uk accents

[JoeWhitwellBBC]

@leihelondon to check with Eimi.

Background
From Sutherland Labs report about transcription performance
"Almost all were impressed with the transcription accuracy demonstrated during the session, however most participants queried how accuracy would be impacted by less studio-quality audio and with accents.

This was a particular concern for those working on World Service shows"

Task
Transcribe accented and non-studio quality audio then work with audio producers to verify if quality is high enough.

Acceptance criteria [Draft]
Producers would be happy working with transcripts.