I haven't had a quote for the fireplace repair yet, as I thought I would see what other bits are hiding in there first. Hoping to open up the rest of the fireplace this week.
I managed to get more of the bricks out today, I found another piece of stone which was wedged into the very top, probably the last piece slid in as it was sealed up. It look as if it was part of something!
There are also 2 iron pieces in the bricks which I'm assuming were part of a hob grate.
Still seems a bit of a bizarre configuration of bricks :?
We finally got the fireplace opened up and we have a total of 3 pieces of carved stone from the front of the fire surround, so not getting it restored. Plus we put up some acro props and started pulling out the rubble, behind it is a layer of plaster which seems to curve outwards, so maybe an old brick oven after all? I think all we can do is take all the loose stuff out and then try to brick it back up.