warming pan 
noun historical
A wide, flat brass pan on a long handle, filled with hot coals and used for warming a bed.Before the second world war he was Worcestershire county golf champion and collected brass warming pans....
- Margaret's was the last royal birth which needed to be witnessed by a government minister, a remnant of the days when changelings were smuggled in on warming pans.
- The warming pan was very popular in the 17th, 18th and early 19th centuries, but by the Victorian period of the late 1830s, more practical answers to the cold bed were being found, mainly in the shape of metal or earthenware hot water bottles.