At the heart of imaginative and effective political science is a desire to comprehend the ‘why’ behind political behaviours and decision making. So far this book has analysed unique data on the basic values of UK politicians to demonstrate that they are psychologically distinct from one another, the general public and their electors. However, public dissatisfaction with British politics often reduces to internalized preconceptions about the immorality or corruption of MPs’ political behaviour (Bowler and Karp, 2004; Allen and Birch, 2015b). In order to understand (a) how MPs interpret and respond to the formal and informal institutions of elite politics and (b) the extent of their personal agency in politics, this book now turns to examine the relationship between basic values and parliamentary behaviour. A rigorous extant literature has iterated the importance attached to values as central aspects of the self and as behavioural codebooks (eg Rokeach, 1973; Schwartz, 1992; Feather, 1995; Verplanken and Holland, 2002; Bardi and Schwartz, 2003). There is no reason, then, why this same logic should not help to illuminate the behavioural decisions and intentions of our political elites, especially those behaviours that are planned and temporally free from immediate constraint (see Eyal et al, 2009).

In addressing the second overarching ‘problem’ posed in this book – Do politicians’ personal characteristics matter for their behaviour once they are elected to parliament? – this chapter makes a theoretical and an empirical contribution. It starts by reviewing the landscape of existing parliamentary studies in the UK and makes the case for a more holistic model of elite political behaviour that accounts for psychological as well as institutional explanations. In particular, it argues that the latter circumscribe, but do not eliminate, individual discretion. Data on MPs’ basic values are then used to evaluate political agency in contexts of varying institutional constraint.