In 1919, Britain plucked 68 Turkish officials awaiting trial in Constantinople for suspected involvement in the massacre of Armenians and shepherded them to a military prison in Malta.

The UK envisioned setting up an international court and bringing them to trial, but faced insuperable jurisdictional problems. The suspects were released. Down the decades, Turkey’s notorious denial that the Ottoman government committed genocide against one million Armenians in 1915 hinged on those ‘acquitted’ and ‘exonerated’ Turks in Malta, though of course charges were never brought and there was no trial.

Today, Turkey wields Article 301 of its criminal code to crack down on those who ‘insult Turkishness’ by affirming the Armenian genocide, most notably author Orhan Pamuk, though his case did not go ahead.

This is some of the sobering history in Geoffrey Robertson QC’s excellent book, in which he forensically charts the Armenians’ deportations, or death marches, and sets down a trenchant legal case against genocide.

Britain’s reaction perhaps epitomises the thin-skinned politics the Armenian question engenders. Britain had joined France and Russia in condemning the ‘crime against humanity and civilisation’. Moreover, in 1916 the British government compiled first-hand accounts of the atrocities in The Treatment of the Armenians in the Ottoman Empire, 1915-16.

Author: Geoffrey Robertson QC

Publisher: Biteback Publishing (£20)

Yet from the early 1990s to 2010, Robertson explains, the government’s stance that the evidence was ‘not sufficiently unequivocal’ to constitute genocide and that the events of 1915 were no more than ‘a tragedy’, ‘gave great comfort to Turkish denialism’.

The positions of both Germany and the US are equally ambiguous. Alerted by diplomats that its Ottoman allies intended to exterminate the Armenian race, the Kaiser ‘decided to turn a blind eye in the interests of the alliance’. The Kaiser was ‘certainly complicit’ in the genocide, argues Robertson.

In the US, ambassador Henry Morgenthau and his consular officials in their cache of cables and memoirs offered some evidence of Ottoman government guilt. While presidents Ford, Carter and Reagan all denounced the massacres, Bill Clinton and George W Bush would only refer to ‘mass killings’ or ‘massacres’ rather than genocide. Barack Obama uses the term Meds Yeghern (‘the great calamity’).

All of this has particular resonance this year as we approach the centenary of the massacres. While the parliaments of many countries have declared that the 1915 massacres and deportations amounted to genocide, Robertson provides balanced treatment of Turkey’s genocide denial, stemming from its Foreign Ministry’s website.

But Robertson concludes that Turkey should ‘acknowledge the crime against humanity, at the very least and make a historic apology’.

While there is a surfeit of first world war titles, Robertson has filled a gap on the Armenian question with this readable and erudite account.

Nicholas Goodman is a sub-editor at the Law Society Gazette