The 10 Downing Street Guard Chairs are two antique chairs. In the early 19th century, 10 Downing Street was guarded by two men who sat outside the building in leather chairs made by Thomas Chippendale. There was a drawer underneath the chair which was filled with hot coals to keep the guards warm whilst on duty. The chairs were made with a circular back and hood, both to shield the guards from bad weather and to improve the surrounding acoustics, thereby allowing the guard to hear better from a wider angle.
10 Downing Street Guard Chairs Wikipedia
The chairs still exist to this day. One of them (also known as the Hall Porter's Chair) stands in the entrance to 10 Downing Street; the other is owned by a private collector of furniture. In the adjacent picture, fraying of the inner arm rests is evident. This is the result of the guards' pistols repeatedly rubbing against the fabric during their watch.