He 'fell on his sword.' He failed to account for taxi expenses totalling £11500. It's been rumbling on for the past year and it was difficult to actualy pin anything on him (as no one could prove he had abused funds, but probably had) and it was expected that it would soon fall out of the news cycle. But a constituency chairman poll showed he had lost support of the party and he rather unexpectantly resigned. He has been a good leader and the only one in parliament who was able to hold McConnell to account, epecially with the slow death of the SNP. If more than one candidate wants to replace him, it goes to a member ballot. So I get to vote in two Conservative leadership campaigns
The irony.