Southampton as a Port and city has had a long history of administrative independence of the surrounding County; as far back as the reign of King John the town and its port were removed from the writ of the King's Sheriff in Hampshire and the rights of custom and toll were granted by the King to the burgesses of Southampton over the port of Southampton and the Port of Portsmouth; this tax farm was granted for an annual fee of £200 in the charter dated at Orival on 29 June 1199. The definition of the port of Southampton was apparently broader than today and embraced all of the area between Lymington and Langstone. The corporation had resident representatives in Newport, Lymington and Portsmouth. By a charter of Henry VI, granted on 9 March 1446/7 (25+26 Hen. VI, m. 32), the mayor, bailiffs and burgesses of the towns and ports of Southampton and Portsmouth became a County incorporate and separate from Hampshire.
What date was the charter regarding Southampton's tax farm signed at Orival? (If the question is unanswerable, say "unanswerable")
29 June 1199