Charlie Powell did indeed make his on-screen debut this evening.
There was a pre-recorded item with Kylie Pentelow chatting to him whilst wandering around behind the scenes in the newsroom, gallery etc. They avoided referring to the fact it's in Bristol, keeping the item neutral enough to be shown on the "Plymouth" edition of the programme.
Similarly, when they demonstrated how chromakey works (Kylie called it "green screen". Ugh) they used a pan-regional map, with place names from the Isles of Scilly to Swindon labelled.
They mentioned that Charlie has been a meteorologist for 10 years. He doesn't look old enough, to me! Must've started before he'd even done his GCSEs!
They called it green screen because it is a green screen, and green is the best colour to use, because it's an easier colour to avoid in clothing terms, than the other common chromakey colour of blue.
Chromakey is a technical term, where as Green Screen is a name that is pretty easy to understand. The screen is green and you digitally replace the screen. It's a good name.