A Charles II Silver Treasury Inkstand, Maker's Mark NW star below (Rev Jackson, p. 138), London, 1681

of rectangular casket form raised on four ball feet, with two centrally-hinged flat covers and an oval swing handle, engraved on one cover with contemporary arms within crossed plumes, the other cover with matching later crests under a Baron's coronet, the interior fitted with a removable sander and inkwell with glass liner, with a division for seals and pen compartment, sander scratched on base initials EB

The arms are those of Bucknall of Oxhey, Watford, co. Herts, impaling Graham for Sir John Bucknall, knighted 23 February 1685, Sheriff of Hertfordshire, 1692, M.P. for Middlesex 1697, and his first wife Elizabeth, daughter of Thomas Graham of London; the couple were married 9 February 1685 in Westminster Abbey. 

The later crests are those of Estcourt, presumably for Thomas Estcourt, who married 6 February 1773, Jane, eldest daughter of James, 2nd Viscount Grimston.  The latter had married Mary, daughter of William Bucknall.  The sander is scratched on the base EB presumably for Sir John's wife, Elizabeth

Sir John Bucknall, by descent to
Mary Bucknall, married James, 2nd Viscont  Grimston, to their daughter
Jane, married Thomas Estcourt 1773
Sir John Noble, Bart.
Sir Andrew Noble, Bart.
Christie's, London, 24 November 1943, lot 13
James Oakes, London, 1959

Queen Charlotte's Loan Exhibition of Old Silver, Seaford House, London, 1929, item 314, p. 37.
Loan Exhibition of Old English Plate and Decorations and Orders to Benefit the Royal Northern Hospital, 25 Park Lane, March, 1929,  item 30, pl. XII.

base split at where joins side caused by pressure by removalbe inkwell, inkwell with old repairs to interior, otherwise good condition
In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective qualified opinion.
NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING CONDITION OF A LOT, ALL LOTS ARE OFFERED AND SOLD "AS IS" IN ACCORDANCE WITH THE CONDITIONS OF SALE PRINTED IN THE CATALOGUE.

Charles Oman in Caroline Silver, p. 57, explains the derivation of the term "Treasury" inkstand.  The term applies to a rectangular casket with double lids with a central hinge which also carries a handle "because there still survives divided between the Treasury and Privy Council the pieces made as a result of the following order issued by the Lord Chamberlain on May 13, 1686: 'These are to signifie unto you his Maty's pleasure tha you provide and deliver for his Maty's service in the Council Chamber in Whitehall these particulars of silver plate.  One silver standish for his Maty being double standish weighing one hundred and forty ounces or thereabouts after the pattern already allowed you, also twelve single standishes for the use of the Lords of Council'."
A treasury inkstand is listed next to the entry for this maker's mark in Jackson's Silver & Gold Marks, rev. ed., 1989, p. 138.