we have the removable fireplace
Tomorrow it may not work.
I’ve cut the food tray as an interference fit in the fireplace surround opening, holding tiled area quite surprisingly firmly in place. With the grate attached inside the chimney breast it offers an anchor to the whole thing.
Considered sticking grate with its front directly into the fireplace surround and jamming the card grate into its home but it didn’t fit as firmly as this arrangement.
Will see if its OK when dry tomorrow or Thursday, but so far so good.