PMQs Verdict: Why David Cameron wants to avoid the televised debates

If you want to know why David Cameron wants to avoid the televised election debates with Ed Miliband you only need to watch their encounter during prime minister's questions today.

The Labour leader's performances at prime minister's questions are at best hit and miss but just occasionally he is highly effective against David Cameron. Today was one of those occasions.

The session followed in the wake of the cash for access scandal and Miliband devoted all his questions to a Labour motion calling for a ban on all MPs from holding paid directorships or consultancies.

The prime minister doesn't want to do this for the obvious reason that it would hit the pockets of large numbers of his own MPs. However, this is not an objection that is likely to win favour with the public in an election year. Two recent polls found overwhelming support for banning MPs from holding second jobs and no prime minister wants to be seen as the defender of high wages for politicians.

So instead Cameron resorted to his default stance of repeatedly pointing to the relationship between Labour and the trade unions.

"The difficulty with his specific proposal is that it would allow somebody to be a paid trade union official, but it wouldn't allow someone to run a family business or a family shop."

The right for MPs to run corner shops is obviously a matter of great personal concern to the prime minister. After all, who hasn't seen their local MP dashing back from Westminster to restock their shelves with canned goods? However it was the question of trade union officials that really concerned him. Unfortunately for Cameron, this was an objection that Miliband had anticipated.

"Well let's agree now to rule out any MP being a paid trade union official, a paid director, or a paid consultant," replied Miliband. "Say yes and we can restore the reputation of this House."

This was clearly not something Cameron had expected him to concede.

"It's not the only problem with his proposal…" he stumbled, before insisting that his real concern that the proposals might stop MPs like Tristram Hunt from giving lectures.

Again, the question of the Labour education spokesperson's part-time lecturing commitments must be a matter of great pressing concern to the prime minister. Hardly a day must pass when he is not worrying about how Tristram Hunt can get by. However, it was the continuing question of Labour's relationship with the trade unions that still dominated his thoughts. Asked again by Miliband to agree to Labour's new motion, he instead repeated his earlier objection that they would allow MPs to be paid as trade union officials.

Given that Miliband had just seconds ago told him that he wants to ban MPs from being trade union officials, this seemed a strange objection, but it was apparently the only objection the prime minister had prepared.

Pressing his point home, Miliband repeatedly called on Cameron to say yes or no to the proposals.

"You can vote for two jobs or you can vote for one. I will be voting for one. What will he be voting for?"

This was not a question Cameron could honestly answer, so he instead returned to once again to his pressing concerns about trade unions.

It's not often you see Miliband smiling in the chamber, but after today's exchanges he sat back with a rare look of contentment spread across his face.

Just occasionally, Miliband has a clear victory in the Commons. But while very few people ever get to see these sessions, millions more would see the election debates if they go ahead. It is for this reason that David Cameron is willing to risk almost anything to avoid them going ahead.