Thanks, good point that it might need replacing in not too long and could be addressed then. I'll also consider the paint and other options to draw attention away. I'm sure with lots of books on the built in a when they go in, there will be some distracting colour and thinking a white ledge across the mantel to tie in the new built ins on either side ... We had been considering changing stone surround to some painted white panels, but thought stone might be warmer/ more character. I've seen some inspiring pictures in this thread and on houzz. Thanks all!

Ah, I wouldn't think so. Photo B is the external side of the chimney, which would have originally been outside the house (the external wall). So i'm guessing your living room was added onto the house at a later stage. So it was never designed to be a double sided fireplace, like some are. And yes, it is a structural part of the chimney. By the way, your bedroom fireplace is a beautiful original mantle, I wouldn't touch it.

Maybe I'm weird , maybe I'm lazy -- I liked that 'busy' look . Even more so after reading what you had to do to change it . And just me , but I find some irony in most people saying the tin didn't suit the period , but then you've turned the fireplace into a book case ! I assume the old air-con was biffed ( i.e. no value ) , and while I do like the new unit , just for my own interest I would have taken the old cover off and painted it a bright gloss red , and done the tin the same . If you don't like red , then go your favourite colour -- yellow or a nice green or blue . If your favourite colour is grey or off-white then I can't help you haha ! If that still looked naff , and you did all the work that you have , personally I would have added some character back in -- I would have 'recreated' the tin area in tiles . IMO even gloss white 150 x 150 would have looked pleasant and added interest without looking too busy , BUT again just me , I would have gone more for a period reddy burgundy , or an emerald green or mottled-toned blue -- I liked the tones in the tiles back in that era ! Obviously , you are happy with what you've done , and you're definitely not going to change it , but just outlining the lines I would have considered .

Yes, I agree with mummagabz. There are lots of Houzzers here who are happy to provide their opinions, but most are not qualified. There are lots of Houzzers here who are qualified running small businesses who will only offer free advice if it may be some benefit to their business (like potential future engagement, or exposure). If you just want free advice (and no more) the qualified Houzzers who are running small businesses probably won't be rushing over themselves to help you. Best of luck, Dr Retro Dr Retro House Calls/Dr Retro Virtual Visits.