NavList:

Many thanks to David Pike for jolting my mind.

Flinders' book says:

"At noon a projecting head two miles long, which, from the lumps of rock at the top,
I called Cape Knob, was three miles distant; and our observations and bearings of
the land were then as under;

Latitude, observed to the north and south  34° 35' 26"
Longitude by time keepers,                119  15
The cliffy projection past Cape Riche,
with Mount Rugged behind it,            N. 75 W.
Two rocks, distant 7 or 8 miles,        N. 56 W.
Cape Knob, eastern extremity,           N. 11 E.
A cliffy projection further eastward,   N. 46 E.
One of the Doubtful Isles,              N. 54 E."

and:

"As the wind veered round to the west and southward, we steered more in for the
north side of Doubtful Island Bay; and at noon, our situation and the bearings
of the land were these:

Latitude, observed to the north and south         34° 16' 40"
Longitude by time keepers                        119  47
Doubtful Isles, south extreme, dist. 11 miles, S. 55  W.
West Mount Barren,                             N. 77½ W.
Middle do.,                                    N. 25  W.
East do., the furthest visible land,           N. 28  E."

So I am fairly sure his T.K. notation must refer to longitude position by 'time keeper'.

Thanks to all.