One model was Diana.
The value of a 12 gauge NR Davis and Son single shot shotgun actually depends on a couple different things. The condition and age of the shotgun would be highly important in determining the value.
I have a Davis & Sons, Davis Warner Arms Corp, side by side 12ga In fair condition and it is valued at $200.00. In excellent condition it would be worth about $295.
NR Davis and Sons operated from 1893 to 1917. Is that close enough?
Some did, but not all.
the internet
Ripley, nr Woking in Surrey
50-125 or so
There isn't going to be any, unless you find an old catalog. The NR Davis Gun Co bought the Warner Gun Co in 1917 and began producing guns marked Davis Warner Arms Co. Shortly after, the Crescent Firearms Co bought the company and produced guns under that name from parts already manufactured, until Crescent was bought by Stevens Arms.
0-150 USD depending on exact configuration, age, condition, accessories, etc..
Wall hanger to 125 USD or so
Probably from around the turn of the century. Value about 100 USD.
No, there is no such element Nr