Hello TomandTabitha and welcome to RootsChat.
There is a Book Of Trades published in 1804, London, Printed for Tabart and Co, which includes pages for Hairdressers. I can see it on the Gale Primary Sources data base (which I access online from home through my Australian National Library card), I'm sure other libraries have similar arrangements.
Not sure about the John Souter version, when and where was it published?