To understand libertarian politics, it is best to think of it as the modern iteration of the classical liberal tradition, which is the ideology of ‘liberal radicalism’ that has always appealed to small numbers within right-wing party politics. However, this ideology also espouses a distinct political project which seeks to emulate Marxist proselytizing tactics by creating a libertarian activist base that can push for policy change within sympathetic right-wing parties. Surprisingly, this radical worldview does occasionally exert influence over mainstream right-wing parties, and libertarian ideologues within their ranks have, at opportunistic moments, been able to encourage their desired laissez-faire policy change. So, why does this libertarian influence fluctuate within mainstream right-wing party policy? Why are libertarian activists within the centre-right able to deliver on their preferred policies at some critical periods but not during others? Through a comparative case study of three European countries (i.e., Iceland, Ireland, and the United Kingdom) this thesis focuses on the interaction of political crises with pre-existing policies that contradict liberal ideological preferences, as the primary explanatory factors for the fluctuation in libertarian influence. It hypothesises that libertarian ideologues can best pursue their objectives within mainstream right-wing parties when a political crisis interacts with pre-existing policy that contradicts liberal ideological preferences. This creates the necessary conditions for libertarian ideologues to convince party moderates to embrace a more libertarian policy programme, as both a solution to the current crisis and as a response to the perceived failure of policy that contradicts liberal ideas. But the same interaction of independent variables can lead to conditions in which ideologues will fail to convince party moderates to embrace libertarian policy solutions or, at other times, these same ideologues will have to disguise their true ideological preferences in order to remain competitive within a mainstream party. This study finds the evidence to support the theory is most pronounced in plurality electoral systems, which should prompt further research.