the rectangular shelf with radius corners above cushion moulded frieze and jambs and roundel end-blocks, raised on block feet,

This “Bullseye” design  – as it is often called – is a ubiquitous Regency design that proved popular into Victorian times. This particular example – a one-piece fixed size surround is ideal for upper floor situations with narrow chimney breast or restricted niche where it is often difficult to find a fire surround small enough. So – if it fits, buy it! – fire surround solutions for narrow fireplaces are rare. Note the early hand-made nuts and bolts on the back.