The overmantle has four bevelled glass mirrors on each  side of the central mirror
 (which is not bevelled).
Carved lattice decorations run across the top of the  overmantle and also at the top of each of the side  sections.
At some earlier stage in its life, the top of the sideboard has been modified....
 Although the overmantle and sideboard work very well together, it is clear they were not originally a matched pair.

However, they are sufficiently similar in design and period, and with very similar carving work, to complement each other very successfully.

The bevelled glass Mirror Overmantle
See the triple line carved horizontal and vertical  trims....
Bevelled glass mirror detail...
The bow fronted drawers slope down gracefully to meet the overarching footwell at the bottom of the sideboard.
The carvings are detailed and precise, with motifs of  curved leaves and precise dots representing lacework.  Note the dovetailed joints.
Bow fronted Sideboard with mirror overmantle 
This item (circa 1930's) is a beautiful example of a  carved sideboard.
Click thumbnails to enlarge photos