Detail from Scene in a London Street
There is sadly not a lot of information to be found on John Collet (or sometimes Collett), but he painted some of my favorite views of common people in the later 18th Century. He was a very prolific artist with many of his works made into engraved prints, but it appears that not much is known about him and his works have never been collected into a book (that I can find, anyway). He has been called the Hogarth of his era, which is apt because his subject matter and often satirical portrayals are very similar to Hogarth's, though some say Collet's pictures lack the moral lessons of Hogarth's.
Here are some of his works which can be found online, and which you will likely recognize if you study this period:
The Elopement (Wikipedia)
Scene in a London Street (Wikimedia)
High Life Below Stairs and The Jealous Maids (sometimes The Rival Maids) (Austenonly.com)
The Female Orators (Lewis Walpole Library)
The Rake's Party (Wikigallery.org)
A slideshow of 8 Collet paintings including The Female Bruisers and The Recruiting Sargeant (BBC)
Proverb Reversed (liveauctioneers.com)
The Bold Attempt (invaluable.com - scroll down to lot 42)
There are many more engravings to be found at the Lewis Walpole Library, too.