Created by celebrated London clock-maker, Thomas Mostyn, the Mostyn Tompion Clock was produced to celebrate the coronation of joint monarchs King William III and Queen Mary II in 1689.
Currently on display in the British Museum in an exhibition coinciding with the 300th anniversary of Mostyn’s death, the clock – which shows the hours and minutes as well as the days of the week – continues to keep good time and runs for more than a year on a single wind.
Noted as much for being a work of art as for its mechanical works, the case features an ebony veneer, silver and gilt brass mounts and is crowned with a statuette of Britannia and a shield combining the crosses of St George and St Andrew while decorations on the four corners commemorate the union of the United Kingdom and depict a rose, thistle, lion and unicorn.
The clock was kept in the Royal Bedchamber until the death of King William III in 1702 after which it passed to Henry Sydney, the Earl of Romney and Gentleman of the Bedchamber and Groom of the Stole. It was later inherited by Lord Mostyn (hence the ‘Mostyn’ Tompion) and remained in that family until acquired by the British Museum in 1982.
Keep an eye out for upcoming famous Londoners on Thomas Tompion.
The clock, featured in the The Asahi Shimbun Display, is on display in Room 3 of the British Museum until 2nd February, 2014. Entry is free.
WHERE: British Museum, Great Russell Street (nearest Tube stations are Russell Square, Tottenham Court Road, Goodge Street and Holborn); WHEN: 10am to 5.30pm daily; COST: Free; WEBSITE: www.britishmuseum.org.
PICTURE: © The Trustees of the British Museum
Exploring London 
I hope they had plenty of notice about the upcoming coronation. A stunning decorative clock would have taken ages to design and create, not to mention bringing in goldsmiths and other artists.
Now my complaint. Queen Mary might have wanted to defer to her husband constantly, but she was the legitimate ruler; he was more than a consort _only_ because that was her condition for leaving the Netherlands. So it makes me really annoyed that William bequeathed a fantastic piece of small engineering (and art) to HIS friend in court.