QVC The Derbyshire Rifle Volunteers Officers button

Volunteers Victorian Officer’s Button — by Smithson & Brigden of Derby
A very unusual silver-plated officer’s button of the Derbyshire Volunteers, surmounted by a Victorian Crown over a strung bugle horn, with “DERBYSHIRE” above and “VOLUNTEERS” below within a raised rim. The backmark, struck in an arc, reads “SMITHSON & BRIGDEN · DERBY ·” with the original copper-alloy shank intact. The silver plating has worn through on the high points to reveal the warm gilt-brass beneath, giving the piece its characteristic two-tone Victorian patina.

This makes the button effectively a retailer-marked private purchase officer’s button, almost certainly supplied directly to a Derbyshire Volunteers officer being measured for his full dress uniform at Brigden’s Derby premises.
The Derbyshire Rifle Volunteers
The Volunteer Force was raised across Britain in 1859 following the assassination attempt on Napoleon III, when fears of a French invasion swept the country and the regular army was scattered across the Empire on garrison duty. The Secretary of State for War, Jonathan Peel, authorised the formation of Volunteer Rifle Corps, and the Duke of Devonshire was asked to raise the force in Derbyshire.