It might be hard to remember now, but there was a time when it was trendy to like Shami Chakrabarti. In the mid-2000s, amid the Iraq War backlash and the furore over identity cards, speaking well of the barrister and head of the human rights campaign group Liberty was a handy way of displaying liberal credentials. She was everywhere: Question Time, Desert Island Discs, Have I Got News For You. A young indie band from Worcester called the Dastards was so keen on her that it even wrote a song about her. It included the lyric: “I turn on my TV/The only one I want to see/Is Shami Chakrabarti.”

The daughter of Bengali immigrants, Chakrabarti was born and brought up in the outer-London borough of Harrow, where she attended a comprehensive school before studying law at the London School of Economics. Her background was a great strength of her campaigning, and during the most authoritarian years of New Labour government she burnished her reputation.

Fast-forward to 13 September 2016, when Chakrabarti made her House of Lords debut as a Labour peer. Baroness Chakrabarti of Kennington wore a sombre expression and a rope of pearls looped round her throat beneath her ermine robe. It was hard to recognise the civil liberties campaigner who was once called “an anarchist in a barrister’s wig” by Loaded magazine.

Yet Chakrabarti has also been cast in another role that is far less desirable than a seat in the Lords: that of a hypocrite. On 29 April this year, Jeremy Corbyn announced that Chakrabarti would chair an independent inquiry into anti-Semitism and other forms of racism in the Labour Party. The inquiry was prompted by the suspensions of Naz Shah, the MP for Bradford West, and Ken Livingstone, for making offensive remarks that were condemned as anti-Semitic. On 16 May Chakrabarti announced that she was joining Labour to gain members’ “trust and confidence”. She said that she would still run the inquiry “without fear or favour”.

The Chakrabarti inquiry delivered its findings on 30 June at a press conference in Westminster. The atmosphere was febrile – there were verbal clashes between the activists and journalists present, and the Jewish Labour MP Ruth Smeeth was reduced to tears. The report stated that Labour “is not overrun by anti-Semitism, Islamophobia or other forms of racism” but that there was an “occasionally toxic atmosphere”. It listed examples of “hateful language” and called on party members to “resist the use of Hitler, Nazi and Holocaust metaphors, distortions and comparisons”. Many Labour supporters were surprised that the report’s 20 recommendations did not include lifetime bans for members found to have shown anti-Semitic behaviour.

Then, on 4 August, it was revealed that Chakrabarti was the sole Labour appointment to the House of Lords in David Cameron’s resignation honours. Both Chakrabarti and Corbyn have denied that the peerage was discussed during the anti-Semitism inquiry. But critics suggested that her acceptance undermined the report and its independence.

In particular, it attracted criticism from members of the UK’s Jewish community. Marie van der Zyl, vice-president of the Board of Deputies of British Jews, said: “This ‘whitewash for peerages’ is a scandal that surely raises serious questions about the integrity of Ms Chakrabarti, her inquiry and the Labour leadership.” A home affairs select committee report into anti-Semitism in the UK has since found that there were grave failings in the report for Labour.

Two further incidents contributed to the decline in Chakrabarti’s reputation: her arrival on Corbyn’s front bench as shadow attorney general and the revelation that her son attends the selective Dulwich College, which costs almost £19,000 a year in fees for day pupils (£39,000 for full boarders). She said that she “absolutely” supports Labour’s opposition to grammar schools but defended her choice to pay for selective education.

Chakrabarti told ITV’s Peston on Sunday: “I live in a nice big house and eat nice food, and my neighbours are homeless and go to food banks. Does that make me a hypocrite, or does it make me someone who is trying to do best, not just for my own family, but for other people’s families, too?”

This was the end for many of those who had respected Chakrabarti – the whisper of hypocrisy became a roar. As the Times columnist Carol Midgley wrote: “You can’t with a straight face champion equality while choosing privilege for yourself.”

Hypocrisy is a charge that has dogged the left for decades (both Diane Abbott and Harriet Harman have fallen foul of the selective school problem). The trouble with having principles, it is said, is that you have to live up to them. Unlike the right, the left prizes purity in its politicians, as Jeremy Corbyn’s squeaky-clean political image shows. Shami Chakrabarti started the year with a campaigning reputation to rival that of the Labour leader, but her poor decisions have all but destroyed her. It’s difficult to recall a time when a liberal icon has fallen so far, so fast.