I had the "pedal squeek" happening when letting the pedal up. I was convinced it was the pedal squeeking but after trying oil on the pedal mechanism it just kept re-occuring. Then on lifting the bonnet and listening with the door open it was loud from the engine compartment. Definately the clutch slave cylinder. I recorded it.
excellent post and most helpful video!
and thank you for confirming that you can indeed “hear a sound from the gearbox end from inside the car as the pedal moves” (my situation too)

I shall investigate under my bonnet and see if i can see whether it is the same arrangement in my 2016 TA 4x4 (is yours a 1.2 and did you have to remove any plastic covers?)