[Note 240.1] once on a time … growth of Manchester image . The population grew 8-fold from 22,000 in 1771 to 180,00 in 1821
Manchester 1834
Fisher's Drawing Room Scrap Book, 1835
Artist: G. Pickering - Engraved by: T. Higham

[Note 240.2] The Irwell rapidly became one of the most polluted rivers in the world. Edward Corbett, the Borough Engineer of Salford, wrote in his 1907 book The River Irwell of his father's experiences around 1819, of seeing "large shoals of fish, chiefly gudgeon but also other fish, rising to the flies" from a vantage point on New Bailey bridge, (now Albert Bridge) in Manchester. Local industry dumped toxic chemicals into the river, such as gas-tar, gas-lime and ammonia water, and by 1850 fish stocks had all but disappeared. In 1860 the Irwell was described as "almost proverbial for the foulness of its waters; receiving the refuse of cotton factories, coal mines, print works, bleach works, dye works, chemical works, paper works, almost every kind of industry." 
https://ontheirwell.wordpress.com/irwell-history/

[Note 240.3] Manchester Zoological Gardens opened in 1838

[Note 240.4] The Salford old bridge is taken away, and clapt a new one in, sir

[Note 240.5]  The station in Newton Lane opened in 1839. It was initially called Manchester Oldham Road but later renamed Victoria Station.

[Note 240.6]  The Bolton and Manchester Railway opened in 1838. Large numbers of stations were being built at the time of this song. Manchester was soon encircled by termini.

[Note 240.7] A mayor and corporation to govern the old town, Manchester was incorporated in 1838 under the Municipal Corporations Act 1835 https://en.wikipedia.org/wiki/Manchester_City_Council

[Note 240.8] Manchester Borough Gaol (also known as Belle Vue Prison was opened on Hyde Road West Gorton in 1849. This does not agree with the proposed site of Brown Street which is in the city centre.
http://www.manchester.gov.uk/directory_record/212407/prison_records/category/1363/land_and_buildings

[Note 240.9] The Theatre Royal as built in 1840. The celebrated clown Joesph Grimaldi had appeared in Manchester in 1811 and 1813
http://www.arthurlloyd.co.uk/ManchesterTheatres/ManchesterTheatresHistoryLesson.htm

[Note 240.10] In former times our cotton swells were not so mighty found, sir,

[Note 240.11] This may be an implication that the "ladies" are prostitutes.