Q&A: Tory treasurer Peter Cruddas donation row explained

Conservative Party co-treasurer Peter Cruddas has resigned after newspaper revelations. Here's a guide to what has happened, and what the political party funding rules are:

What has happened?

What did he promise the undercover reporters?

What cover story were the reporters using?

Who is Peter Cruddas?

Why did he resign?

What did Number 10 say?

So were any laws broken?

So what's so wrong with what he suggested?

What's been David Cameron's reaction to the revelations?

What can donors normally expect from the Conservatives?

What has been the political reaction?

Haven't the other parties had similar problems?

Haven't they all been talking about changing the rules?

So is it going to happen?