To look into the ethics of a person re-mortgaging their fully owned home so that they can claim the interest off the tax payer.
Why is this important?
To see if the morality of the rules around expense claims matters more than the letter of the law. To show how he did this here is a helpful video from the bbc to explain.
https://www.youtube.com/watch?v=wPqG7MjPwic