What is a centre engine? - You may ask. A centre engine would normally drive a Carousel (or for the sake of British terminology, a set of Gallopers) and is obviously located in the centre. The object with unpainted wooden panels (located beside the engine) would normally be the very centre of the carousel/gallopers and, as you could imagine, the engine would drive it.
This photograph was taken at Dingles Fairground Village, near Launceston.