This chapter about the UK Parliament by Ruth Fox was part of the Parliamentary Effectiveness programme. It asks: What is the role and function of a backbench MP, and are there differences in approach in different legislative systems? What shapes their scrutiny role and work, and how are these factors affected by constitutional, electoral, personal and political circumstances at both constituency and legislative level? Drawing on examples from a range of parliaments in South Asia and beyond, the chapter explores what conditions enable backbenchers to exercise influence and conversely what constrains them. Looking at examples from the renaissance of backbench rights at Westminster in recent years, it identifies the kind of institutional reforms that can promote a more inclusive and accountable legislature. But it concludes that ultimately new procedural rules and powers cannot make backbenchers more effective if they lack the political will and determination to hold government to account. Backbenchers must be willing to use the procedures and powers at their disposal.