They made an election promise around university tuition fees. When they were elected and become coalition leaders they reneged on that promise, and then continued to fuck over their core voters (bringing in damaging NHS budgets; really awful benefit reforms (and refusing to investigate increase in death by suicide linked to those reforms) etc.
They got in by focusing on marginal seats. They lost most of those in the last election. They used to get protest votes, but those went to UKIP or the green party, or even labour or conservative.
> Because it seems to me like a bulk of these supposed Blair-ite 'Labour' supporters
It's the labour MPs who want to get rid of corbyn. He's very popular with the party members.