Political biography - handmaiden to history?

Biographers are producing many good accounts of political lives, but are they fully realising the genre's potential to contribute to understanding the political past? Often these biographies are constrained by limited aims that make them more handmaidens to history than central players. Many political biographies are predominantly a narrative of a life, leading to anodyne conclusions that can be little more than character assessments of the subject. Why is this so? And how might political biographers achieve more? A wise choice of subject is just one such means; the main need is for stronger assessment of a subject's policy ideas, achievements and lasting influence-effectively, to establish the individual's place in history.