The last one is Daniel & Arter Ltd, Birmingham, about 1890. Mass-produced silver plate. “Nevada Silver” is a fanciful name for an alloy of copper, nickel, and zinc.
They are all either electroplate or base metal alloy marks - no silver ones here. You can probably find them all at English electroplate and silver plate: marks and hallmarks of Sheffield makers AA-AZ. As a guide the first one is at JR&S - John Round & Son.
The third and fourth ones, “Brisbane Silver,” are Shaw & Fisher, Sheffield, late 1800’s, and also just silver plate over nickel.
The second one is William Page & Co, Birmingham, about 1880-1890. Also silver plate, worth little or nothing. They used a whole series of amusing marketing ploys, labeling things as “Bolivian Silver,” “Roumanian Silver,” “Silverite,” and “Trevor Plate.” 
Edited to add: I think I might have been at university with Trevor. 