A good old tin fireplace insert which has seen slightly better days. It is quite an unusual model that I haven't seen elsewhere, either in houses or loose, and has an integral mantelpiece (just a bent over bit of the tin). The two bars of the grate seem to have been replace, not very skillfully, but it does look fine from the front. I don't know if it is English or German, but it does have some age. I would guess 2nd half of the 19th century. It is 9.5 cm square x 3 cm deep.
If you are interested please contact me for post, either before or after buying it!