One of the most interesting things I read about leadership in the B628 course book was the observation that modern approaches to leadership see it as being highly contextual. Different leaders taking part and playing different roles at different times. There are no fixed qualities that make one person a leader, and there are no guarantees that one person will be a leader in all situation at all times.
Leadership is about tackling three core issues:
Strategic issues: the results the organisation seeks, including what direction the organisation should take, what opportunites and threats should be considered, etc.
Task issues: the individual tasks the organisation needs to carry out in order for it to achieve its results.
People or maintenance issues: the relationships between leaders and their followers, including morale, motivation, and cohesion.