A voucher (or ticket of admission) to a ball at Almack’s assembly rooms in London. Only society’s elite were granted these coveted passes. To be stricken from the list was social disaster. This voucher to Almack’s was issued in 1817 to Anna Elizabeth Grenville, Marchioness of Buckingham—who obviously cherished it enough to safeguard it for posterity.
A nice little snap shot of history for lovers of Regency romances and/or Regency period history :)