This is a rare c1903-23 vintage C.Y.J.L.C.(South Yorkshire Joint Line Committee)No10 brass The Thunderer Patent Railway Whistle.It is manufactured by a rare maker Henry Riley Constitution Hill Birmingham.It is in a good condition but at one time a couple of splits have been crudely repaired but could easily be re soldered and it comes complete with its original chain.The whistles overall measurements are 5.8cm long x 2cm wide x 2.6cm deep.(p.s.due to its low number it would most probably date from c1903-4).