[1] After leaving school, he was apprenticed with a local chemist until 1891 when, on the inheritance of a small legacy, he then decided to travel to Australia,[2] where he searched for gold and also worked on a sheep station before returning to Scotland in 1902.
Forrest's life then took a most unexpected turn; caught in a shower while fishing the Gladhouse Loch in Tweedsdale, he sought shelter beneath an overhanging bank where he chanced upon an ancient stone coffin.
The discovery led to his introduction to Professor Bayley Balfour, Regius Keeper of the Royal Botanic Garden, Edinburgh, who offered him a job in the Herbarium.
A year later, Balfour recommended Forrest, now aged 30, to Liverpool horticulturist and cotton broker Arthur Kilpin Bulley, who was sponsoring an expedition to southwestern China in search of exotic plants, particularly species of rhododendron, of which Yunnan has many.
He and his team of 17 local collectors stayed briefly at the French mission under Père Étienne-Jules Dubernard in the small town of Tzekou.
In the sanctuary of the rhododendron forests, so rich in variety of flora and fauna, the group was unaware of the massacre that was to meet them on their return to the mission, and that only one would survive.
On 5 January 1932, while hunting game in the hills near Tengchong, the town wherein Forrest traditionally set up his base, he suffered a massive heart attack and died instantly.