39nunney castle39 no 5029 st97801 was designed by the chief mechanical engineer of the great western railway charles collett and was constructed in 1934 at the swindon works the castle class of locomotives was designed for hauling express passenger trains and its official somewhat less catchy moniker was the gwr 4073 class the 39nunney castle39 was one of the 171 castle class engines to be built no 5029 taking its name from a 14th century castle in somerset the 39nunn