Small fortification in the Isle of Man associated with the pre-Revestment garrison establishment.

The office of Commander of Derby Fort appears in the evidence of John Quayle to the Commissioners of Inquiry in 1791. Quayle stated that for several months in 1755 he simultaneously held the offices of Attorney-General, Steward of the Garrisons and Demesnes, Commander of Derby Fort and one of the three officials executing the office of Collector.

The command itself involved very little work. Quayle told the Commissioners that the command of Derby Fort was “almost a sinecure” and carried a salary of £8 Manx currency.

Responsibility for the fort sat within the wider office of Steward of the Garrisons. The Steward directed repairs to the Lord’s houses, forts and castles, provided entertainment at the castle on particular days, supplied ammunition to the garrisons and forts, and supervised carriage services. He received a salary of £8 Manx, while the overseer assisting him received forty shillings.

The offices of Commander of Derby Fort and Steward of the Garrisons ceased at Revestment in 1765. Quayle explained that afterwards a Store Keeper and Overseer of Works was appointed by the Board of Ordnance.