Watch List notes:

Victoria, proof shilling, 1840, young head left, rev. 'face' value within wreath, crown above, date at bottom, milled edge (S.3904; ESC.2984), certified and graded by NGC as Proof-65, attractive deep toning, a nice choice proof of record, mintage unknown but minuscule, struck for placement in museums
The only one graded as Proof-65 by NGC, none higher.

Estimate: 3500 - 4000 GBP