Like so many images of its kind it now has an eerie presence.

Sitting inside the 4x4 vehicle and grinning broadly, the driver is seen surrounded by wires and what might be a detonation button.

The photograph is said to be the last taken of a fifty-year-old man from Manchester who was known at various times in his life by different names.

Born Ronald Fiddler to parents of Jamaican origin, as a Muslim convert he was also known as Jamal al-Harith.

Later, however, his fellow jihadists within the Islamic State (IS) group would give him the nom de guerre, Abu Zakariya al-Britani. Al-Britani means “the Briton.”

This was the name by which he was known when photographed last week before carrying out his suicide car-bombing mission on a military base southwest of the Iraqi city of Mosul.

“The martyrdom-seeking brother Abu Zakariya al-Britani - may Allah accept him - detonated his explosives-laden vehicle on a headquarters of the Rafidhi army and its militias,” read a statement from IS shortly after the attack.

“Rafidha” is a derogatory term for Shiite Muslims, who the Sunni Muslim IS considers to be heretics.

The story of Jamal al-Harith is a shocking one on so many levels. It’s narrative and bloody end on the battlefields of Iraq has once again

highlighted fears over the problems of radicalised jihadists who become foreign fighters for extremist groups like IS and al-Qaeda.

In the light of how he chose to end his life, the case of al-Harith is certainly embarrassing for those who were in the UK government in 2004 and 2010 and for those whose job it was to assess the security threat he posed between 2004 and 2014.

It was back in 2004 that al-Harith was freed from the US detention camp at Guantanamo Bay following intense lobbying by Tony Blair’s Labour government.

At the time of his release, the then home secretary David Blunkett said: “No-one who is returned...will actually be a threat to the security of the British people.”

The story of how he came to Guantanamo Bay goes like this: al-Harith said that in 2002 he travelled to Pakistan on a backpacking trip. While there, he paid a truck driver to take him to Iran. The truck was stopped near the Afghan border. Taliban guards saw his British passport and arrested him as a spy.

American troops discovered al-Harith among numerous foreigners held by the Taliban and released him. He was then detained in Kabul by US forces who found his explanations regarding the purpose of his travels implausible. He was arrested as a suspected enemy combatant and transported to Guantanamo Bay, where he was one of nine British citizens detained.

After his return to Britain, al-Harith was paid £60,000 for a joint interview with a newspaper and television network describing his Guantanamo ordeal.

He also launched a compensation claim against the British government after saying British intelligence operatives knew or were complicit in his mistreatment while in detention. That compensation claim, it has been reported, netted him up to £1m.

But a decade later, in 2014, and despite his high profile, al-Harith was able to travel to an IS-controlled region of Syria, before ultimately carrying out his suicide mission in neighbouring Iraq.

According to figures published by the UK government last year, about 850 people regarded as a national security concern have gone to become fighters in the Middle East.

Of those, just under half have returned to the UK and approximately 15 per cent are now dead.

Right now it remains extremely difficult to confirm the whereabouts and status of many British nationals in these areas. But as the battles for Mosul in Iraq and Raqqa in Syria rage on, many international experts and policymakers have already begun to focus on what the inevitable defeat of the Islamic State group will mean for Europe and elsewhere.

Across the corridors of power in Brussels there is a widespread fear that the collapse of the organisation will lead to a surge in foreign fighters returning to Europe.

“Re-taking the Islamic State stronghold in northern Iraq can lead to a scenario in which violent militants would return to Europe … This is a very serious threat and we must be prepared to face it,” warned EU Commissioner for the Security Union, Sir Julian King.

Similarly, EU Counterterrorism Coordinator Gilles de Kerchove has cautioned that Europe would struggle to handle the predicted 1,500-2,000 foreign fighters who may return when IS is driven out of its strongholds in Mosul and Raqqa.

In only the last few days, Iraqi forces entered a neighbourhood in West Mosul for the first time since launching a major operation to retake the city from IS that began last October.

The army’s assault takes them from desert and farmland into a densely packed city, where the hard core of IS fighters of which Jamal al-Harith was one, are expected to put up the fiercest resistance yet in defence of Mosul, the heart of their self-proclaimed caliphate.

That IS and its foreign fighters are under pressure like never before is now certain.

At its peak, IS drew thousands of recruits each month and controlled about a third of Iraq’s territory, and the foreigners like Jamal-al Harith who poured in from dozens of countries, have been characterised as the most die-hard fighters.

Slowly but surely however IS has lost ground and appeal. Last week documents detailed in the Washington Post after being discovered by Iraqi counterterrorism forces in Mosul’s al-Andalus neighbourhood, revealed yet more evidence of cracks with the jihadists ranks.

The files of 14 “problem” fighters from the group’s Tariq bin Ziyad battalion, made up largely of foreigners, told of some who claimed to be sick and did not want to engage in battle. One fighter from France wanted to leave Iraq to carry out a suicide attack at home while others from Kosovo had requested transfers to Syria. Some had just simply refused to fight.

“He doesn’t want to fight, wants to return to France,” said the notes on a 24-year old listed as a French resident of Algerian descent. “Claims his will is a martyrdom operation in France. Claims sick but doesn’t have a medical report.”

The forms in the file are marked with the year 2015 but appear to have been filled out later. Some specify dates that the fighters joined stretching into 2016.

The details in the files while difficult to independently verify, have been gathered by an organisation that is meticulous in keeping records and provide a fascinating glimpse into the lives of some foreign fighters. They provide personal information like name, country of residency, date of birth and blood type.

They also outline other data like weapons specialities and the number of wives, children and “slave girls” each fighter had. Some files had photographs included.

Faced with the pressures of impending defeat, some fighters are reported to have abandoned IS’s strictures, such as bans on alcohol and cigarettes.

This say some intelligence analysts, has irked those who are more dogmatic about the enforcement of sharia law, creating splits within the group.

Foreign fighters it seems are most affected by the impending collapse of Mosul. As IS forces crumble, these are the individuals with the fewest options. Unlike local members, they cannot remain in Iraq because they stand out among locals and do not speak the language.

For the same reason, it is difficult for them to blend in with refugees. Many now understand that they will most likely die and very soon.

While this has had a galvanising affect on some foreign fighters who have responded with even more religious zeal and determination to

die a shaheed, or martyr, others it’s reported are doing the opposite.

Iraqi soldiers involved in overrunning some IS bases, have reported noticing an increasing prevalence of empty whisky and beer bottles on captured bases.

According to Vera Mironova an International Security Fellow at the Harvard Kennedy School’s Belfer Centre, civilians she spoke with near Mosul told of IS fighters drunk on the streets.

This was especially the case close to the frontline and in areas where Russian and Central Asian IS militants are based. Some top IS commanders are also said to be turning a blind eye to such transgressions and the religious disputes that are resulting are damaging the group’s cohesion.

Many foreign fighters in Mosul, perhaps Jamal al-Harith among them, were housed and pampered at the city’s five star Ninewah Oberoi Hotel in the east of the city.

When IS overran the area it renamed it Hotel Waritheen (Inheritors) and foreign fighters and suicide bombers seen as the group’s most elite and prized members, replaced its once wealthy Iraqi patrons.

With the Iraqi army’s recent capture of the hotel’s ruined compound, they found yet more evidence of IS turmoil and disintegration. Beds are missing from the hotel rooms, reputedly sold by IS fighters in Mosul’s markets.

Though troops found no signs of alcohol here, painkillers and syringes used by jihadist fighters before and after battle lay scattered around its rooms.

Despite these apparent signs of a breakdown in discipline within the ranks of foreign fighters, there is still equally strong evidence of the religious commitment that brought some to the battlefields of Iraq and Syria in the first place.

According to the American authors of one recent academic study entitled ‘Talking to Foreign Fighters: Insights into the Motivations for Hijrah to Syria and Iraq,’ none of the 20 jihadists interviewed cited socioeconomic grievances or other forms of disenfranchisement as a major role in their decisions to wage jihad abroad. Rather, the conversations largely revolved around their Islamist beliefs.

There is other startling evidence too that foreign fighters will continue to play a crucial role in IS and al-Qaeda exportation of global jihad.

The emergence of a small but significant group called Malhama Tactical, marks the world’s first jihadi private military contractor (PMC) and consulting firm.

While far from being an enormous military conglomerate like the infamous Blackwater (now named Academi), it consists of 10 well-trained fighters from Uzbekistan and the restive Muslim-majority republics of the Russian Caucasus.

According to researchers at Foreign Policy magazine, Malhama’s fighting prowess and training programmes are renowned among jihadis in Syria and their admirers elsewhere.

The group has also on occasion acted as special forces for different jihadi groups. Malhama takes its social media presence very seriously, advertising its services through Facebook, Youtube, Twitter and the Russian social media site VKontakte, before its account was suspended.

If the online platform is vital to the promotion of Malhama’s jihadi services then so too will it become vital to IS future survival.

Forced to surrender control of its “caliphate” in Iraq and Syria IS will undoubtedly seek to preserve a virtual version of itself online, keeping its foreign fighters and cadres engaged.

Charlie Winter is a senior research fellow at the International Centre for the Study of Radicalisation at King’s College London and the author of a new report warning that it is premature to imagine a “post-Islamic State world at this time.”

Winter has outlined how the IS media wing has already begun to repurpose videos, images and messages from its massive collection for new propaganda releases that depict the Islamist state it sought to establish as an idyllic realm destined to be restored.

“If compelled to, the group’s true believers will simply retreat into the virtual world, where they will use the vast archive of propaganda assembled by the group over these past few years to keep themselves buoyant with nostalgia,” Winter concludes in his report.

This of course will enable IS not only to continue drawing foreign recruits to the fight in Syria and Iraq, but preserve the loyalties of its dispersed followers.

Already under pressure on both battlefronts, the IS network is currently shifting toward more traditional insurgency tactics.

“Broadly speaking, we’ll see the IS reverting to type, looking more like a run-of-the-mill terror group rather than a proto-state,” says Winter.

Of the more than 4,000 foreign fighters who have left European union nations for Iraq and Syria, around a third have returned, according to the

Hague based International Centre for Counterterrorism.

About 14 percent have been confirmed dead, while the rest remain overseas or their whereabouts unknown.

As the events in Syria and Iraq unfold, it’s clear that Europe’s foreign fighter problem is far from over and the worst is most likely yet to come.

As IS continues to lose ground, we might not just see a reversal of the foreign fighter flow, but also new flows to emerging hotspots. Increasingly, IS is likely to direct resources to its affiliates across Africa and Asia.

In this context, experts and analysts are agreed that now more than ever, it is crucial that governments get to grips with the complex nature of the foreign fighter phenomenon in order to design and implement effective countermeasures.

“The only way to tackle the foreign fighter phenomenon is a comprehensive approach that addresses all dimensions of the threat, while focusing on its most salient aspects,” says Dr Alastair Reed, Acting Director of the International Centre for Counter-Terrorism.

“Thus, a priority on rehabilitating returned foreign fighters needs to go hand-in-hand with emphasis on security-centric measures, such as the surveillance of homegrown networks and sympathisers, to prevent both travel abroad and attacks at home,” insists Reed.

The case of suicide bomber Jamal al-Harith is a powerful wake up call on the urgent need for such measures.

Without them suicide bombers like al-Harith and other terrorists from within the jihadists future franchise, will continue to haunt us both home and abroad.

Don't miss Foreign Editor David Pratt's report next week from the frontline in Mosul.