We've tried glueing it but the glue wasn't as heat proof as promised and it's broken again, leaving a massive hole at the back of the fire (so half the flames are out of sight).
It's a little Victorian fireplace and the firestone (I think that's the right name, not sure) is a pretty specific fit - anyone got any idea where I could get a replacement for not too much ££? Am in SE London/Kent btw. Thanks for your help/ideas.