Sir Keir Starmer's leadership has been tested after more than 50 of his MPs and eight shadow ministers rebelled over Labour's refusal to back a ceasefire in Gaza. In total, 56 Labour MPs defied Sir Keir's orders and voted in favour of an SNP amendment that called explicitly for a ceasefire in Gaza - despite warnings that it was designed to cause "division". They were joined by eight members of the frontbench who, in breaking collective responsibility, were forced to resign from their posts. But why has the issue of a ceasefire caused so much division? And why does the...