what is this 'UNUSUAL PNEUMATIC BOLT ACTION AIR PISTOL' please? (auction lot)

[ccdjg]

It is the first version Eureka, typified by its lack of trigger guard, and it is quite a bit rarer than the later Eurekas with trigger guard, which are more usually referred to as "Bedford and Walkers". This first version also has a more slender plunger rod than the others. Unfortunately in this version the knob missing from the plunger is not just a simple knob but also slides over the barrel, so it is a bit difficult to replace. Not impossible though, and well worth the hassle given the rarity of the pistol. The upper example shows a replacement slider that I made, and the lower example shows a pistol with its original slider.
I would happy to send you details .

PS: Can also help you with details for restoring that British Cub should you want them.