First Nations people and other explorers
The 2008 Management Plan for the Walpole Wilderness and adjacent parks and reserves reported:
Aboriginal people have occupied the vicinity of the planning area [Walpole Wilderness] for at least the past 6000 years. However, evidence from other parts of the south-west suggests this occupation has been as long as 48 000 years. Nyoongar people were transient, but occupied coastal areas more than forests. Traditional lifestyle for Nyoongar people had close links to and understanding of the land. [p 116].
At the time of European settlement, the south-west was inhabited by 13 different socio- linguistic groups. These groups shared traditions and a common language, and are collectively known as Nyoongars. The word ‘Nyoongar’ translates to mean “man” or “person” and relates to the language spoken in the area to the west of a line from the coast south of Geraldton to the Great Australian Bight, east of Esperance. However, considerable variation existed within this group. The group which lived in the planning area were known as the ‘Murrum’ (Crawford and Crawford 2003). These people occupied an area from King George Sound, north to the Stirling Range and the Shannon River and on the coast from West Cliff to Boat Harbour and Palingup River. They also lived around Mount Barker, Nornalup, Wilson Inlet and the Porongorup Range (Tilbrook 1983, McDonald, Hales and Associates 1994). [p 115].
The Timeline of Events compiled by D. Lee Hunter for the Society records evidence of Aboriginal People living in the Walpole area:

Fish traps at Broke Inlet and Wilson Inlet, gnamma holes in rocks in the Gordon River; Frankland River had lizard traps and shallow crab-crushing depressions along the coast. There are also native wells (soaks) eg Nornaculup.
The Timeline also records that (in the early 1800's) visiting sealers and whalers used Sealers Cove and Snake Island in the Nornalup Inlet. Captain Stirling, Governor of the Swan River Colony until 1839, instructed sealers to look out for Deep River of the Sealers.

exploration events: 1791 (Vancouver) and 1841 (Eyre).
On the miniature sheet, the stamp is set against
a period engraving of Eyre's arrival in Albany