Mayday: How the White Helmets and James Le Mesurier got pulled into a deadly battle for truth

The British man behind the Syrian civil defence group, the White Helmets, found himself at the centre of a battle to control the narrative of the Syrian war. Russian and Syrian propagandists accused his teams of faking evidence of atrocities - and convinced some in the West. The battle for truth formed a backdrop to James Le Mesurier's sudden death in Istanbul in November 2019.

With the setting sun reflecting in the water and the lights of Istanbul twinkling on the horizon, the wedding guests sat around lantern-lit tables: diplomats from several countries, military officers, journalists and activists who had flown in from around the world to see James Le Mesurier get married.

A dashing former army officer in his 40s, Le Mesurier had made his name as the co-founder of the White Helmets - the group of several thousand young Syrian men and women who pulled survivors and bodies from the rubble of bombed-out buildings in rebel-held areas of the war-ravaged country.

The woman he was marrying, Emma Winberg, once worked for the UK Foreign Office but had latterly been helping him manage the White Helmets. She was his third wife.