From late 1803 she sailed as a privateer under a letter of marque until the Royal Navy put her under contract from 9 June 1804 to 25 May 1805 as a hired armed ship.

On 22 October 1803, T. Lockyer, Esq., announced he was the sole owner of two of the "most beautiful letters of marque that will sent from any port in the United Imperial Kingdoms of England and Ireland."

[4] The extent of Pretty Lass's armament, the size of her crew, and the fact that she was to sail in company with Lady Charlotte are consistent with her being a privateer.

In reporting the transaction, the Naval Chronicle described Pretty Lass as a ship under the command of Captain Tippet.

"[6] Tippett was still in command on 6 August when Pretty Lass sailed from Plymouth with dispatches for the fleet at Brest.

The last mention in Lloyd's List of a Pretty Lass, armed ship, is that she returned to Plymouth from a cruise on 22 May.

[13] This article includes data released under a Creative Commons Attribution-ShareAlike 3.0 Unported UK: England & Wales Licence, by the National Maritime Museum, as part of the Warship Histories project.