An early work by the artist painted when he was living and working in Liverpool. It is set in the Mersey with the buildings of Liverpool carefully delineated in the distance. The small 24-gun ship in the foreground is shown in broadside port-bow view, making sail, and again in port and stern view in the distance on the right. It is flying the red ensign and a pennant and is requesting a pilot to assist with the passage down river. A pilot cutter is shown on the far left, preparing to respond to the request and another pilot can be seen on the right in the distance. The ship was originally thought to be a frigate because she appears to be heavily armed but the pennant she is flying is not naval but that flown by mail packets. There is some speculation that she may have been a privateer, a privately owned armed vessel intended to operate against the trade of an enemy in times of war. This practice was abolished in 1856. In the foreground to the right, two men are occupied on board their small fishing boat. In a reference to Dutch marine painting, the artist has shown the fins of several large fish (or possibly dolphins) in the foreground as well as a buoy on the left.

Liverpool, like Bristol, came to prominence as an 18th-century slaving and sugar port but overtook this earlier rival as northern industrialization made it one of the main beneficiaries of expanding international markets for British manufactured goods. It remained a 'boom town' for most of the 18th and 19th centuries. The painting displays both technical accuracy and careful delineation, informed by personal experience and intimate knowledge of the sea. This has led to the assumption that Salmon probably supplemented his income as an artist by working in shipping or related industry.

Salmon was born in Whitehaven, Cumberland, where his family probably worked as mariners. He moved to London in the late 1790s and then to Liverpool in 1806. In 1828 he left England for Boston, Massachusetts, where he became a successful painter of marine views, ranging from small panels and canvases to theatrical moving panorama scenes. He returned to Europe about 1840 and died between 1848 and 1851, though where is uncertain. The artist has signed the painting with his monogram 'RS' and dated 1809, bottom right.

A Packet off Liverpool