The engine sits on a wooden and metal plinth measuring 39 x 28.5 x 9 cm. The maximum height of the whole set from bottom of base to top of funnel is 35cm. The moving parts still move freely (see https://youtu.be/idSf8yiQ3cI ). If you hover your nose over it, it still smells of smoke and steam. Based on writing under the base, this appears to have been made in 1987 in Middlesbrough.
Locomotion No.1 was the first locomotive commissioned by the Stockton & Darlington Railway and started work on the 27th September 1825. She served until 1846 until she was sold to Howden Station where she worked as a stationary pumping engine (fitted with pumps from an engine at Middlesbrough) and then in 1850 at West Durham Colliery owned by the Pease family. In 1856 the Pease family invested £50 in restoring Locomotion No.1 to near her original condition (her replacement wheels were not the original spoked type) and after much celebration she was placed on a plinth outside North Road Station in Darlington in 1857 (a Gothic glass case was designed for her but never built). In 1892 she was moved into Bank Top Station in Darlington and in 1975 back to North Road Station which had just been made into a museum.