Air Raid Precautions (A.R.P.) lamps were used in times of blackout during the Second World War. Placed at road junctions, they were to assist pedestrains and vehicles users in conditions of almost total darkness.
These particular designs share the same basic design, but differ in manufacture (note fuel reservoir shapes.) The top section of each lamp is hinged to allow access to the wick and winder, the latter being removed in order to fill the reservoir. (see photo.)
The red version is of the original type built to comply with A.R.P. Department Circular No. 259/1939 of 30 September 1939, requiring lamps to display white crosses, rendered invisible from above, hence the shielded design. This lamp has three cross shaped apertures, behind which is white painted plain glass, held in place by spring clips for easy replacement.
The green version is a later design, patented (see links page) by a Walter George Batt. This features four removable red glasses, (the patent mentions other colours) covered by what are described as "shields". One "shield" has a movable disc (not mentioned in the patent) which uncovers a hole that aligns with a clear circle in the corresponding glass. Once lit this allows the lamp to emit, in addition to red light , a small pencil beam of white light upwards. The purpose of this is unkown, at this time, but may have provided a method of illumination to alllow I.D. cards to be viewed or somesuch.
Finally the blue lamp is of the patented Walter G. Batt "shielded" type where the shields have been removed, along with the red colourant from the glasses (evidence of which can still be found). This type is through to be post war reworking of the "shielded" Walter G. Batt design to produce a hurricane type lamp, from surplus war stock.