HAS a considerable Quantity of LONDON PORTER just arrived at the Duke's Quay, in Barrels and Half Barrels, which is stout, fine, and well flavor'd. He will be obliged to his Friends for their immediate Orders, as laying in a Stock thus early, the Liquor will be far superior in the Spring.
He also sells Commission, LIVERPOOL ALE & BEER, 36 Gallons, and Half Barrels of 18 Gallons; white and Blue BOILING PEAS, of the best Quality. Newry and Belfast BUTTER, of first, second and third Sorts; Derby, and Mansfield MALT; superfine Worcester & North-Clay HOPS; OATS, BEANS, WHEAT and FLOUR, on the lowest Terms; also Barrel CYDER."
Manchester Mercury - Tuesday 19 March 1782, page 1.
First a pretty obvious one: London Porter was being shipped to and sold in Manchester. Since it arrived at Duke's Quay, I think it's fair to assume that it arrived by water.
Then there's ageing. In this case clearly not happening at the brewery in vats but at the customer. I'm trying to work out the timing. The advert appeared in the middle of March - surely that is just about the start of spring? This is confusing. Does it mean spring 1782 or spring 1783 when the Porter would be "far superior"?
Observe also the use of the word "stout" not to mean a specific style of beer but simply "strong". It wasn't until a few decades into the 19th century that "stout" came to be associated with a certain type of dark beer.