History will judge Israel’s apologists the way Theresa May is now judged on apartheid South Africa.

The UK Labour Party’s adoption of the International Holocaust Remembrance Alliance’s (IHRA) anti-Semitism code in full, including its list of 11 examples, means it now considers calling Israel “racist” a potentially racist act.

But the reality is that since the foundation of Israel – beginning with David Ben-Gurion’s “Drive them out!” order to the Palmach in the 1948 Nakba – racial oppression of Palestinians has been the norm.

As Palestinian freedom fighter Ahed Tamimi has observed, Israel is afraid of this truth being known. And by adopting the full IHRA definition, Labour is helping to stifle it.

But we shouldn’t be surprised: UK politicians have a long and inglorious history of protecting states practising apartheid. Notably, they have never been held to account for their support for white rule in South Africa.

We were reminded of this recently when Prime Minister Theresa May visited Robben Island, where Nelson Mandela and many other anti-apartheid activists were imprisoned for decades.

When asked what she had done to hasten Mandela’s release and the end of minority rule in South Africa, she squirmed awkwardly, before claiming “what was important is what the United Kingdom did”.

What the British government – and May’s Conservative Party – did was not only fail to support Mandela and the African National Congress (ANC) but actively support the apartheid South African regime for years.

Following the 1970 UK election, Conservative Prime Minister Ted Heath pledged to end the arms embargo on South Africa and resume military equipment sales to the apartheid government.

In the 1980s, Conservative Prime Minister Margaret Thatcher resisted global pressure to impose sanctions on South Africa and labelled the ANC “a terror organisation”.

In the same era, an aspiring young politician – future Prime Minister David Cameron – went on an all-expenses-paid trip to South Africa courtesy of an anti-sanctions lobbying firm, while members of the Federation of Conservative Students went as far as wearing “Hang Nelson Mandela” stickers.

The UK is as deeply complicit in Israel’s apartheid system as it was in South African apartheid, if not more so.

Adoption of the IHRA’s definition of anti-Semitism by the Labour Party – and the Conservative government, nine months ago – is just the tip of the iceberg.

From its historical role in smoothing a course for the ethnic cleansing of Palestine by issuing the Balfour Declaration to its contemporary arms sales to Israel, when it comes to Palestine the UK stays true to its colonial past.

Israel is afforded impunity despite its multiple crimes, such as the killing of over 160 Palestinians in Gaza since the Great March of Return began. The UK seeks to protect Israel from accountability in global forums like the United Nations, for example by refusing to vote for an independent investigation into the killing of 60 Palestinians on May 14 this year, a massacre dubbed the “Palestinian Sharpeville” after the 1960 murder of 69 black protesters by South African apartheid security forces.

Regardless of Israel’s long-standing disregard for international law and grave human rights violations, Britain even gifted it a royal stamp of approval in June when Prince William made a symbolic visit to the country, contravening seven decades of British policy against official royal visits to Israel.

History is repeating itself. Just as the UK government shielded South African apartheid in the past, it is giving political, economic and military support to Israeli apartheid today. In 2017 alone, the UK government granted more than 289 million British pounds-worth ($375.3m) of licenses for the export of arms and military technology to Israel.

But in the end, British support didn’t protect South African apartheid from the reach of justice and equality. Similarly, the IHRA won’t protect Israel’s ethnocracy.

Palestinians and their allies will continue to name the racial oppression they face under Israel for what it is – a system of apartheid. And history is already beginning to repeat itself in another, more positive, sense.

Just as a powerful global boycott movement helped make South Africa a pariah state – in the process making a vital contribution to ending apartheid – the Palestinian BDS campaign is following in its footsteps.

The BDS movement understands that freedom, justice and equality will not be handed down from above by the very same politicians who have tolerated Israeli apartheid for so long. It can only be won by pushing from the grassroots up.

Thirty years from now, British politicians will be asked what they did to end Israeli apartheid. And though the UK’s complicity will no doubt be similarly whitewashed, history will judge Israel’s apologists the way Theresa May is judged now on South Africa.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.