This is a fine example of a 20th century Officer of the Watch style telescope engraved 'B. COOKE & SON LTD, HULL' on the first draw. It was made by clockmaker and optician Barnard Cooke who founded the company in 1867, and the brother of the better known instrument maker Thomas Cooke of York.

The business moved several times from its original Hull premises, expanding successfully into chronometers and sextants, eventually being sold to Henry Hughes & Son in 1918. Likely dating to the early 1950s, the main barrel is covered in its original dark brown leather stitched cladding which is in excellent condition and the draw tube and fittings are nickel plated brass with some minor plating loss, but in dent free condition.

Although a single draw telescope, it has an additional pancratic tube to provide variable magnification in three stages of 16x, 18x and 21x, and whilst this is not uncommon for field telescopes, it's not often found in Officer of the Watch style telescopes.

All lenses are clean and free of any damage, producing a clear and sharp image through the 40 mm diameter objective lens, which is protected by an attached leather end cap, whilst the eyepiece has an integral swivel dust cover.

A classic style of Naval telescope in very good condition, it measures 17½" (445 mm) closed, 27½" (700 mm) fully extended with sliding sunshade and weighs just over 1 kg.