I'd definitely go for installing a simpler Edwardian reclaimed fireplace. You can find those on ebay or in reclamation yards.. but avoid one with lots of fussy detail. I'd then sand it and paint it a dull pewter (or sand) colour personally. See Marston and Langinger paints - they're lovely. OR use a duller silver paint spray (found in Car accessory shops) as you obviously like the chromed mirror.. which might go on another wall to balance out. I added an Edwardian fireplace to my blocked up chimney breast (so much healthier for the chimney too) and I simply couldn't believe the difference it made to the vibe of the room. It almost said 'OH! Thank you!' to me!!!!!!!!!!!!!! and immediately felt authentic again.

Tip! If you can't find one that has a lower ash tray bit, just slot in a piece of ply (as your carpet is beige) under the grate to provide a sense of floor continuity. I used a grey engineered wood tile in my room and it works brilliantly.

Amazing advice thank you! Have a reclaimed fireplace to see today so hoping that will do the trick :)