[1] His siblings were older sister Barbara and younger brother George Hamilton Dennistoun (23 September 1884 – 16 June 1977).

[3] In March 1910 with Jack Clarke and Lawrence Earle he made first ascent of the 2,875-metre-high (9,432 ft) Mount D'Archiac in the Southern Alps.

[2] In 1911 Dennistoun walked in to Milford Sound from Lake Te Anau over McKinnon Pass, and inquired among the track porters in the hope of finding someone to climb the peak with him.

None of the porters had any climbing experience, but one of them, Joe Beaglehole (1875–1962), had read Scrambles among the Alps by noted climber Edward Whymper and was thus chosen by Dennistoun to accompany him.

Unfortunately to avoid climbing back over the Footstool, they decided to descend straight into Sinbad Gully, which meant they had to resort to using a rope to lower themselves down bluffs.

Christie and G. Raymond completed the third ascent in 1941, they found remains of the handkerchief, as well as two halfpennies left by Murrell and Williams.

Pennell mentioned that he wanted someone to take charge of the seven Himalayan mules donated by the Indian government which they would be carrying south to the expedition.

During an expedition in the Southern Alps in January 1914 by Dennistoun, his brother George and Sydney King they discovered and named the 2,065-metre-high (6,775 ft) Terra Nova Pass which overlooks the Havelock and Godley Valleys.

At first he served as an intelligence officer but after a few months was seconded to the Royal Flying Corps, joining the newly-arrived No.23 Squadron as an observer.

Another member of the squadron was Dennistoun's cousin, pilot officer Herbert Bainbrigge (Herbie) Russell (1895–1963), and the pair were permitted to fly in the same plane.

[2] Their aircraft encountered engine problems and they returned to base only for their commanding officer to demand that they take another airplane and continue with the raid.

[15] The two airman were reunited at Biache and taken on 5 August to the hospital in the Ohrdruf prisoner of war camp in central Germany.

St Stephen's Church in Peel Forest has a stained glass window donated by Dennistoun's mother, Emily in 1923.

The face of St Michael is a portrait of Dennistoun and in the bottom pane is a small representation of Mitre Peak.