Yes - as I remember The Sontaran Experiment emerged when the reworking of John Lucarotti's The Ark in Space into Robert Holmes's version jettisoned all the location recording, which became a new story on its own but with the same director and I think other crew too. It tapes first (I'm careful not to say filmed here, for obvious reasons) because location recording was usually done before studio, which remained with The Ark in Space.

I agree with you about the use of 'arc' too...