WW2 Clip-On Helmet Lamp

I recently purchased this Ever Ready clip-on helmet lamp. I'll be renovating the lamp by stripping it back to bare metal and removing the rust etc. I have seen quite a number of unused helmet lamps in boxes for sale. These are marked Lamp Spot Electric or similar and a number have the War Department crow's foot / broad arrow emblem imprinted on them. I'm currently uncertain whether these lamps (every example appears to have a red and black cord) are post-war items. Perhaps someone can recognise the order number as something post-war.

The battery container on the Ever Ready version has the same Patent Number on the bottom as the hooded lamps that have a 1939 date on them. I assume Ever Ready simply used existing stock of battery boxes for the clip-on helmet lamps.

It appears versions of the helmet lamp with a plain cord are relatively scarce compared to those with red and black cords. 

I've also only encountered a relatively low number of period photos that show the helmet lamp being used. This photograph is probably one of the best.

WW2 Clip-On Helmet Lamp

Lamp Spot Electric with Helmet Clip

Lamp Electric Steel Hemet