Denis MacShane was a politician of passionately held convictions whose career ended in the most humiliating fashion.

The Commons Standards and Privileges Committee found that his abuse of the expenses system was the “gravest case” called to its attention.

Most painful of all, for this veteran campaigner against fascism and antisemitism, was the fact that his original accusers were the British National Party.

Mr MacShane has apologised for his “foolish mistakes”. He remains upset that, in his view, he was judged so harshly for the way he submitted false claims for his work in Europe and in fighting antisemitism.

There has been understandable anger at Mr MacShane’s apparently casual attitude to the use of public money for his own personal projects, however admirable the causes may be.

The media lawyer Mark Stephens leapt to his friend’s defence and warned of the danger of handing a high-profile scalp to fascists. This is indeed a risk.

Denis MacShane’s fall from grace has been a blow for those who share his concerns about extremist politics, whether it is radical Islamism in the Middle East, neo-fascism at home or the rise of ultranationalist groups in Eastern Europe.

He has been an eloquent voice on these issues and it is in no one’s interest, apart from his enemies, that he will no longer be able to pursue them in parliament.

Readers of the JC will know what a good friend Denis Macshane has been to the Jewish community. His chairmanship of the All-Party Parliamentary Inquiry into Antisemitism was exemplary and established beyond doubt that prejudice against Jews remained a very real phenomenon in modern Britain and Europe.

Since the inquiry published its report six years ago, Mr MacShane has remained vigilant in monitoring the situation. His resignation does nothing to undermine this groundbreaking work, nor should it deter others from taking up the cause he championed.

He recognised that his parliamentary career was over as soon as the Commons committee reported its findings — and he was right to resign. He was more than cavalier in his attitude to expenses.

The Jewish community has lost a champion in parliament and, like all Mr MacShane’s friends, people will feel disappointed by the manner of his leaving the House of Commons. But I know he will continue to battle against antisemitism because he doesn’t know how to stop campaigning.

It is not often that I find myself quoting Oprah Winfrey. But she once said: “Lots of people want to ride with you in the limo, but what you want is someone who will take the bus with you when the limo breaks down.”

Will the Jewish community take the bus with Denis MacShane? It is at such times that friendships are truly tested.