A 19th century mahogany-cased marine chronometer by Parkinson & Frodsham

A 19th century mahogany-cased marine chronometer by Parkinson & Frodsham. Having a 3" silvered dial with Roman hours and Arabic minutes, engraved "PARKINSON & FRODSHAM Change Alley London 1975" over running seconds dial at VI, the four-pillar chain-driven single-fusee movement with blued steel helical spring of nine turns, diamond endstone, and keystone weights, the spotted backplate engraved "Parkinson & Frodsham Change Alley London", within brass cowl with blued steel cruciform base spring, the brass gimbal beneath screw-fitting convex-glazed bezel, the hinged three-part box with dust-cover, brass bale handles and ivory escutcheon plus two plaques, the smaller vacant, the larger engraved "PARKINSON & FRODSHAM LONDON", 6", (15cm) width, height and depth.