Clan system not formalised, “protection” of chief in return for service esp military. Gaelic idea of duthchas (loyalty). Pressure was increased prices with Napoleonic wars and debts, due to elites trying to maintain lifestyle with minimal revenue. Against emigration recruitment initially (people as assets) instead Sheep introduced. given crofts with limited (inadequate) land and encouraged to fish or collect kelp. Markets for both failed, then potato blight hit. Unlike Ireland, most chieftains actively involved in relief efforts but now liability.
Chieftains now try to call themselves landlords, and encourage emigration in exchange for arrears. Sense of divine punishment for sins rather than breach of clan duty, only later seen as unjust (as other campaigns against landlords become prominent, and as nationalism develops). Former Jacobite military often leading emigration recruitment (as clans demilitarised post 1745). Ex-army often given chance to own land in colonies and keen to attract workers.
[In our time, BBC Radio 4]