This is the world's first railway roundhouse, built 1800 – 1839 by Robert Stephenson for the North Midland Railway. It was described on construction as "A polygon of sixteen sides, and 90 ft (58m) diameter, lighted from a dome-shaped roof, of the height of 50 ft (15 m).
Offices with a clock turret were included on one side. The clock is an 1840 John Whitehurst ’Arm Chair Strike’ clock
The weathervane with its engine is over 6ft long. If the engine is one that was built at the Derby works I have not been able to find out
The Seat back shows an outline of the roundhouse that, due to the high fence, I was unable to successfully photograph
