Trump trial: This was Donald with his trousers down - no doubt

There are moments, more than others, that scream the humiliation of it all.

Take this, before Tuesday's proceedings got underway. "No descriptions of genitalia or anything but it's important to elicit that she had sex with him."

It was the prosecution's assurance prior to questioning Stormy Daniels after Donald Trump's lawyers had objected, in advance, to her testifying to the details of sexual acts.

It would be that kind of day in this kind of trial.

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In a dingy New York courtroom, this was the president and the porn star, together again, in a reunion most reductive for Mr Trump.

He might have secured guarantees on anatomical detail but, from the moment the court heard "The People call Stormy Daniels" this was Mr Trump with his trousers down, no doubt.

Ms Daniels told her story, of growing up in Baton Rouge, Louisiana, the daughter of a single mother. She edited her high school newspaper, enjoyed ballet dancing and horses and had ambitions to be a technician.

By the time she met Mr Trump, aged 27, we learned she was an adult film actress and director, star of the likes of 40-Year-Old Virgin and Knocked Up.

By her telling, the Trump encounter was more Austin Powers - the penthouse suite, the satin pyjamas and the spanking with a rolled-up magazine.

"Bullshit," Mr Trump was heard to mutter. His problem is that this kind of bullshit sticks.

Whatever his lawyers' protestations about Ms Daniels' credibility - and there are holes - that's hardly the headline for a watching, voting, public.

What will they take from court to the polling booth in November? Quite apart from the imagery, what message does it send to key demographics?

An affair with a porn star, whilst married, is a poor fit with the principles of evangelicals, so critical to the Trump vote in 2016. Suburban women might also reel from this tawdry peek backstage at the presidency.

How much will Mr Trump worry? About $130,000 (£103,000) worth. It is the premium he paid to stop the story coming out in the first place.

Sadly, for him, the insurance policy has run out.