Michael summarises the book in this way
This well set out book by John Whitehead, formerly the Shire Engineer at Coonabarabran NSW, maps and relates in exquisite detail one of the lesser-known expeditions of the English-born botanist and explorer Allan Cunningham (1791–1839). In 1825 his small party trekked from today’s outer north-west Sydney north to the Hunter Valley. They then followed the route of an earlier (1823) botanical tour to Pandoras Pass in the north-west. Then they entered the south-west sector of the vast Liverpool Plains, the second party of colonists ever to do so.For those who do not know Michael, he describes himself as an independent scholar. I know his work and he displays a punctilious eye for detail. That is partly why Mr Whitehead's book appeals to him - like appeals to like! I do not disagree.
The real advantage of work such as this is that it allows detailed tracing of the journeys of the early explorers. When I first studied Australian history I found this stuff fairly boring. I suppose I saw the explorers more in terms of what would come, not realising what an important resource they were in describing the land before it was changed by European occupation. Now as a regional historian, they have become a major resource.