Despite giving one of her most pro-Israel speeches to the audience at the Jewish News/Bicom Balfour 100 event, the Shadow Foreign Secretary, Emily Thornberry, left listeners in no doubt where she stood on the vexed question of whether the Balfour centenary should be “celebrated” or “marked”.

Answering a question from the Unite union leader Len McCluskey, Ms Thornberry said unequivocally: “We should mark Balfour by recognising the state of Palestine”.

He response, however, was later pooh-poohed by Sir John Jenkins of the International Institute for Strategic Affairs, who dismissed the idea as “gesture politics, what people do when they haven’t any idea what else to do”.

In her remarks, Ms Thornberry, who took the place of Labour leader Jeremy Corbyn at the Balfour 100 banquet held on Thursday evening, said that she frequently reminded her colleagues that “Labour’s support for Zionism and the establishment of a Jewish State pre-dates even the Balfour Declaration, stating plainly that this state must be open ‘to which such of the Jewish people as desire to do so may return and work out their salvation, free from interference by those of alien race and religion.’”

Modern Israel, she said, “still stands out as a beacon of freedom, equality and democracy, particularly in respect of women and LGBT communities, in a region where oppression, discrimination, and inequality is too often the norm”.

In a meeting with the Mayor of Tel Aviv in the summer, the Shadow Foreign Secretary said she had been “proud to congratulate him on the success of Tel Aviv Pride, which welcomed over 200,000 people under the rainbow flag”. And she noted, grimly: “Contrast that with recent events in Egypt, where even the waving of that flag at a pop concert was enough to prompt dozens of arrests and calls for the criminalisation of same-sex activity”.

She said she saluted “the resilience and strength of the Israeli state and the Israeli people against all those who have sought to harm and destroy them: a resilience that has had constantly to adapt as the threats over the years have changed from the conventional warfare of 50 years ago to the ever-shifting tactics of terrorists today”.

And she made clear, as she had when speaking to the Labour Friends of Palestine at the party’s Brighton conference in September, that “anyone who believes in a two-state solution loses all right to a hearing if they simultaneously indulge those who deny one of those states its very right to exist”.

Nevertheless, the Shadow Foreign Secretary maintained, Balfour’s Declaration contained “unfinished business”. She observed: “We see actions taken on a daily basis that seem to entrench division ever deeper, to the point where the gap will be impossible to bridge”.

Such actions included “the despicable practice of glorifying terrorism to children, by naming schools after suicide bombers”, or “the way in which support for illegal settlement-building and the demolition of Palestinian homes has become almost a political purity test for some in the Knesset”.

She concluded: “While marking this centenary, we must also be honest and say that – until Jewish communities all over the world are free from the threat of terror, and the scourge of anti-Semitism, until the rights of the Palestinian people are secure and we have a viable, secure, internationally-recognised Palestinian state, living side-by-side, in peace and security, with the state of Israel, then the work that Balfour started cannot be considered complete”.

Taking questions, a slightly startled Ms Thornberry agreed that Labour leader Jeremy Corbyn was a Zionist — if Zionism was the belief in a Jewish state of Israel, she said, then “of course, it’s self-evident” that Mr Corbyn was a Zionist.