I’d remove the small tiles on the fascia and all the tiles above that. Add a wooden mantel. Good luck.

I suggest removing the tiles and start over

I'd rip the whole thing out, it's ugly as hell. Put something you like there.

why don't you check out some of the American renovating programs which have wonderful fireplace makeover ideas, what style is your house

Another option would be to put a TV on there , judging by the plant you don't light it often , if at all , and that may distract the eyes .

I sort of like that the tiles aren't absolutely perfect , but there looks to be a couple of gaps along 'in front' -- I'd try grout , or plaster and then paint when dried , almost go for the craft look .

And maybe its just the light , or camera flash , but the left wall looks to have a blue tinge , the skirting board looks lighter on that side too , and the hearth step thing a different colour again -- I'd go black/charcoal on that step thing , and make sure all the walls are the same , if they aren't .

what style are you using in your older home, traditional or. Your tiling looks a bit Californian to me

I'd also remove the tiles above and put a mantel in. It looks quite ugly as is, but if you made it a little more traditional it would make a big difference. You could just prep the tiles to tile over the top but it would look a lot better if you removed them all and replaced them. If you like the grey, the mantel may just be enough to make it work.

I don't mind the tile. For me it's the unusual display items that don't compliment the fire place.
I would purchase some dark or black pieces, maybe pots for your plants, and put these in the place of the current items.
Maybe, a chunky darker wood or white mantel would also improve the look. Again changing the displayed items.