Use of term "flash mob" dates back to 1800s Tasmania?

Wikipedia defines "flash mob" as

[A] group of people who assemble suddenly in a public place, do something unusual for a brief period of time, and then quickly disperse. They are usually organized with the help of the Internet or other digital communications networks.
But blogger Derek Lackaff found a postcard (above) that indicates earlier use. The collaborative mooning of a Tasmanian prison official by several hundred pissed-off, underwearless women, from A SINGULAR ACT OF FEMALE REBELLION IN VAN DIEMEN'S LAND in 1844:
But when Mr Bedford, whose hypocrisy had earned him the ridicule and contempt of his female flock, and especially that of a group of hardened offenders known to Hobart Town as `The Flash Mob,' began to address the women from the dais, "on a sudden the three hundred women turned right round and at one impulse pulled up their clothes shewing their naked posteriors which they simultaneously smacked with their hands making a loud and not very musical noise.

This was the work of a moment, and although constables, warders etc. were there in plenty, yet 300 women could not well all be arrested and tried for such an offence and when all did the same act the ringleaders could not be picked out. The feeling of the Governor and her Ladyship may well be conceived..." – although it was said that her Ladyship managed to restrain her mirth until she was safely homeward bound in the viceregal carriage.

Would that today's flash mobs were that interesting. I love the illustration. Note the governor's wife stifling her laughter with a white-gloved hand. Link (Thanks, Alex Halavais)

Reader comment: xiaolongnu says,

I'm an art historian by profession, so the first thing I noticed was the style of the image on the postcard. The pseudo-engraving on this postcard is done in a style that is clearly modern, not 19th-century. Obviously somebody was trying to imitate a 19th-century newspaper engraving, but this is not a reproduction of a period image. Thus the postcard itself (which is obviously modern) can't be considered evidence for the usage of the phrase "flash mob" in the 19th century. It may represent a later urban legend in Hobart, or it may reflect an actual usage from the past. The thing to do would be for a historian to locate "Rev. Robert Crooke's diary." If *he* used the phrase "flash mob" that would be proof of its 19th-century provenance. Similarly, a newspaper article from the period, etc., would serve as evidence -- but, sadly, this postcard does not. Does anybody have evidence for actual 19th-century sources that the postcard might be drawing on?
Derek, who blogged the postcard, replies:
Google reveals that the image is a 2004 painting by Tasmanian artist Peter Gouldthorpe. The Flash Mob is an actual historical phenomenon -- more details about this group and Tasmania's other female convicts here: Link
meika loofs samorzewski in Tasmania says,
I live about a kilometer away from the "Female Factory" (prison) where the incident occurred. Part of it is a memorial to the hundred of women and babies (The area was called the Valley of the Shadow of Death for this reason) At Cascades in South Hobart, Tasmania.

Whatever the age of the card the term "flash mob" referred to a real group of people, convicts and and local born, mostly young,who dressed 'flash' and were uppity and rude etc etc in New South Wales and Van Diemen's Land. In Aboriginal English today you can still here "pretty flash" for well dressed, well done as a general term of excellence.

The term mob is Australian English as the accepted collective noun for a group of Kangaroos, from the hoitytoity mobilus vulgaris. It has a wider usage than just "mob violence".

The Governor in question is the same Franklin who led the ill-fated expidition to find the North-West Passage and the whole crew went mad eating lead-sealed canned food and perished. He and his wife while governing Tasmania were the yuppies of their day, Romantic and capable. The story is the clash between two subcultures educated and refined Romantic yuppiedom and the 'flash mob' that the picture card illustrates. Some Links: from here,

"Watkin Tench, officer in the marines, commented not long after the arrival of the First Fleet, on the fact that the convicts were marked by their use ‘of what is called the flash, or kiddy language’, an ‘unnatural jargon’ that needed to be abolished in order to achieve reformation. The ‘infatuating cant’, he believed, was ‘more deeply associated with depravity, and continuance in vice, than is generally supposed’. Tench reflected the views of the British elite of the eighteenth century, who associated the lower classes with criminality, and despite their concern with reformation exhibited a voyeuristic fascination with the habits and culture of the so-called criminal class."

See also The Australian National Dictionary Centre, and Tassie Terms: A Glossary of Tasmanian Words, as well as Wikipedia entries for Female Factory, John Franklin, and Van Diemen's Land.