Well all I have come up with is a transcription of the Napoleonic War Records 1775 - 1817
The year is 1803, William Scott of the 66th Foot, status is given as substitute, county is Wiltshire. The reference is E182/1099(pt2).
There is no image to look at which may give further information. As I have never looked at any Napoleonic War Records no idea what information would appear on the original document.
This was from Find My Past.