He began travelling to America in 1739 but returned permanently to his home town from 1757, living at Cross House in Linlithgow.

His term was noted for extensive dealings with Native American tribes on the colony's western and southern borders.

Glen stayed in Britain to protest this change, and William Bull acted as governor in his stead.

He was also responsible for promoting an official policy that aimed to create in Indians an "aversion" to African Americans in an attempt to thwart possible alliances between them.

[2][3] During King George's War, Glen sent a trade delegation led by notable Indian trader and historian James Adair to win over and convince the Choctaw chief Red Shoes to abandon the alliance with the French and to side with the British.