I have a note that the order abolishing queues was issued in July 1808. As I recall the information was in a history of the 15th Foot which I cannot lay my hands on at the moment. The history noted that the 15th, being stationed in the W Indies, were one of the last units to wear the queue as they did not receive the order for some time.

I wonder if the date you have given is for a second promulgation of the order.

DE Graves