The experience and expertise of the membership has greatest impact in the exercise of the persuasive, rather than the coercive, capacity of the House.  (The distinction is fairly straightforward, but for anyone interested it is developed in my Parliament in British Politics [2005].)  That is, members have greater impact in persuading ministers of the merits of the case rather than through imposing their will in the division lobbies.  Each parliamentary year (session), usually between 2,000 and 4,000 amendments are secured to Government Bills in the House of Lords.  Well over 95% of these are secured through agreement: in other words, there is no vote.  The occasions when amendments are achieved through a vote are very much the exception and not the rule.

When there is going to be a vote, then the task of ministers is to persuade other parties in the House, rather than individual members, to support them.  As the research of Meg Russell has shown, it is the Liberal Democrats who hold the balance of power.  Cross-benchers are more numerous than Liberal Democrats, but – for the quite understandable reasons given by Baroness Murphy in her early post – cross-benchers have a much lower voting turnout.   In Wednesday’s vote on a referendum on the Lisbon Treaty, for example, it was the votes of the Liberal Democrats that determined the outcome, not the votes of the eight cross-voting Conservative peers. 

Votes in the Lords are less frequent than in the Commons, and when peers vote they are actually less rebellious than MPs in their willingness to vote against their party.  (They do, though, have the greater luxury of being able to stay away.)   However, when Government supporters rebel, they have the greater potential to affect the outcome, given the uncertainty of many votes.  The outcome, though, is more often detemined by parties than individuals.

For anyone interested in looking at the academic literature, may I modestly recommend: Philip Norton, ‘Cohesion Without Discipline: Party Voting in the House of Lords’, The Journal of Legislative Studies, 9 (4), 2003, pp 57-72.  It’s a racy little piece.