The blinds were lowered, blocking the impressive view of Parliament Square usually visible from Portcullis House’s conference rooms.

All eyes focused instead on the slight woman sitting at the top table.

“I’m seeking your help today,” Shami Chakrabarti told the two dozen journalists who had gathered for the official launch of Labour’s independent inquiry into antisemitism, which she chairs.

Within 15 minutes her plea was discarded as her integrity, and that of the investigation itself, came under intense scrutiny.

After a series of smugly-delivered comments about how quickly she would report — clearly intended as a dig at the overdue Chilcott Inquiry — Ms Chakrabarti was forced on the defensive.

She suddenly resembled a rabbit caught in the headlights

There was a sense of quiet astonishment among the media pack as the former barrister admitted she had joined Labour on the very day she was appointed to her inquiry role by party leader Jeremy Corbyn.

When is a supposedly independent inquiry not independent? Presumably when the person leading it is a member of the organisation she is investigating, and repeatedly says she will act “for and in the best interests” of that organisation and its supporters, as Ms Chakrabarti was at pains to say on Monday.

What about the best interests of the Jewish community and the many Jewish party members, activists and parliamentarians who have expressed their disgust at the series of allegations of the past three months?

Vice-chair Baroness Royall sat stony-faced throughout. A day later she would publish the conclusions of her own investigation into allegations against Labour students at Oxford University.

That probe was carried out without any questioning of her impartiality, despite being a Labour peer — a position that some have suggested Ms Chakrabarti may be aiming at after completing her own probe.

Amid her protestations that her independence would be maintained, Ms Chakrabarti attempted to explain why she had joined Labour. She wanted, she said, to avoid a political row.

Was she worried that some Labour supporters might think she was secretly a Conservative? Ironically her decision has almost certainly caused her inquiry far greater problems. Later she appeared to admit her “judgement” may have been wrong.

One reporter skewered Ms Chakrabarti by quoting a JC story relating to her vice-chair David Feldman’s backing of the Independent Jewish Voices group.

Turning to a prepared statement, the 46-year-old attempted to continue unflustered, but she suddenly resembled a rabbit caught in the headlights.

Professor Feldman, sitting next to her, grinned continuously — speaking only to confirm that he was not a Labour member.

Another reporter asked Ms Chakrabarti whether she and her co-chairs had agreed on which definition of antisemitism they would adopt. This was a thinly-veiled reference to Prof Feldman’s past efforts at defining Jew-hate. Last year he dismissed regularly used definitions, including the European Union version widely adopted in political circles.

Prof Feldman also believes the Macpherson definition of racism which followed the Stephen Lawrence Inquiry was “built on weak foundations”.

This is the explanation that says if a Jew finds a comment or action to be antisemitic, it should be considered, or at least investigated, as such.

Ms Chakrabarti refused to say what definition would be adopted. To add to the farce, 24 hours later Baroness Royall recommended the Macpherson definition should be used — putting her at odds with her fellow co-chair.

The broadening of the Chakrabarti inquiry to include “Islamophobia and other forms of racism” was also questioned. It is no longer an investigation into antisemitism per se — it will have a wider scope. Why? Ms Chakrabarti said it would “seem strange and lopsided” not to consider racism more generally.

It was pointed out by one journalist that Seumas Milne, Mr Corbyn’s spin doctor, had previously confirmed that Labour had received no allegations of Islamophobia and had not suspended any members for anti-Muslim comments or actions.

“I don’t consider it a dilution of the inquiry,” Ms Chakrabarti insisted. The Jewish community may feel otherwise.

So what did we learn? That this is an inquiry into antisemitism which will spend a portion of its time reviewing other forms of racism; has no agreed definition of what is antisemitic; no formal powers to compel witnesses or impose sanctions; has a vice-chair whose suitability is widely questioned; and a chair who has inexplicably raised doubts about her own credibility.

“I do not have the power to make anybody do anything,” Ms Chakrabarti acknowledged.

Whether her inquiry will carry any weight, offer any answers to her party’s problem with antisemitism, or even cross the finishing line, hangs in the balance.