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Quote from above webpage
" A plant on a windowsill experiences a stronger light gradient than does a tree outdoors, where gravitational cues can overpower more subtle light-direction cues. Indoor plants get a lot more light on one side than on the other, which activates photoreceptor molecules to a much greater extent on the lit side. This difference is biochemically translated as a growth response, known as phototropism, which makes the plant bend toward the light.

Trees growing at a latitude of, say, 60 degrees ( further to the south near the south pole) are also asymmetrically illuminated because of the slant of the noon sun—approximately 55 degrees at the beginning of the summer growth season—but the difference in light intensity there is smaller and more variable. The modest light gradient experienced by the tree is counteracted by a continuous gravitational influence, known as gravitropism, which guides plant growth upward.

The strength of gravitropism trumps phototropism in the tree scenario but not on the windowsill. The edge of forest gaps provides a good place to observe light-guided tree growth at any latitude. There the effect of a strong light gradient can be seen in the reaching of trees into the gap."

To which someone writes - Keith Labreque 5/8/2009

Quote "The relevance to the topic is that because the earth spins at a very high surface speed, one would think that at a mid-latitude of perhaps 45 degrees the centripetal acceleration would alter the direction of apparent gravity noticeably. It does not, however, because in reality the centripetal acceleration is miniscule compared with local gravity. So although plumb bobs there don't hang vertically, and trees there don't grow vertically, the effect is so small you cannot observe it. "

My comment,
This debate about photos of leaning trees at Stringybark Creek can be dismissed as irrelevant. Photographic camera distortion, and the will of the photographer to create a balanced composition, i.e., unlevel ground verses upright trees will always be a challenge.

Plumb bob exercises? I would assert that even with accurate laser pointing apparatuses set on stable level tripod to gauge the lean of a tree or trees SBC, would show insufficient lean in a general sense except for young trees growing on the edge of a clearing as the professor said,
" The edge of forest gaps provides a good place to observe light-guided tree growth at any latitude. There the effect of a strong light gradient can be seen in the reaching of trees into the gap."

We have to remember when Burman took the photo, all the mature trees were part of an undisturbed forest around that time, and before any part had been cleared, and no trees would have developed a lean during the short time period since the clearing there. We can be pretty sure the lean of any trees at the Burman photo spot were leaning left or right and every which way according to the 'then' forest canopy and that no particular pattern could be attributed to the effect of the sun arcing through our northern sky. Therefore, to try to determine where the police camp was by testing the lean on mature trees in photos and current circumstances is not a viable theory.

Bill Denheld

Also Google - early Old cameras could correct for non parallel distortion

Examples of cameras that can correct for parallel distortion.
Burman's camera was earlier than this one below, but the principle of bellows allows for correction of what would be vertical walls or trees as in Burman's scene of SBC to be seen as vertical structures that would otherwise appear to be leaning inwards. Modern digital cameras generally don't have such features except for very expensive ones that have higher quality lenses specifically designed to reduce distortions such as for photographing buildings and to keep straight lines straight. These days with digital photography, distortional correction can be done easily with computer software.
Example of early cameras from Google images.

This image shows a typical correction of parallel distortion. Burman would have done the same corrections when taking his shots at Stringybark Creek, so the photo looked right.

This camera left was more like the type Burman would have used and was a simple version of the later compact cameras shown above.

The function still allowed parallel distortion to be minimised with the sliding hinged mounted lens.