GWR Large Hand Lamp

Great Western Railway oil lamp built at the company works at Reading to the design of the more common signal lamp but with an unusual carrying handle and internal orange lens filter. Please advise if anyone knows the specific purpose of this lamp variant?Lamp is complete and in totally original ex-railway service condition with the expected small knocks, dents and glass chips - you will get your fingers dirty and still smell the unique aromas of the long gone ''Steam Railways''. The correct internal burner lamp is stamped ''GWR READING'' on the door and the brass burner engraved ''GWR''. Ready to be filled with paraffin to begin another 80 years of service. H: 320mm, Diameter 190mm