Arrested in the two dowdy hotels in Aden on 24 December the five defendants, with another man travelling on an Algerian passport, are portrayed in Britain as innocent victims, tortured into confessions by the Yemeni police, and in Yemen as fanatical Islamic terrorists, acting on orders from London.
This is not an easy case to understand. It is heavily influenced by the confrontation between Britain and Yemen over the bloody outcome of the kidnapping of 16 tourists east of Aden last month. Three Britons and an Australian were killed during a rescue attempt by the Yemeni army.
The trial also takes place against a background of Yemeni government fury at the presence in Britain of Abu Hamza al-Masri, who preaches at a London mosque and is the leader of the Supporters of the Sharia (Islamic Law) group. One of the defendants, Mohsin Ghalain, 18, is Mr Masri's stepson and his full son, Mohammed Mustapha Kamil, is on the run in Yemen.
Mr Masri is the one uncontested link between the five Britons and Abu Hassan, the leader of the kidnappers. In the hours before he killed the hostages Abu Hassan used his mobile phone to ring the sheikh in London for advice. By his own admission Mr Masri told him that he should "spare Muslim blood", coming close to instructing him to kill the non-Muslim tourists.
None of this is in the interests of the men on trial - Malek Nasser Harhra, 26, Samad Ahmed, 21, Shahid Butt, 33, of Birmingham, Ghulum Hussein, 25, of Luton and Mohsin Ghalain, 18, of London - all of whom were staying in hotels in Aden in December. They protest that they were there to study Arabic and one of them was planning to get married.
Their first actions gave no ground for suspicion. On 19 December three of them checked into a hotel called al-Wafa. They almost immediately checked out. Days later they were back and the same night police burst into the hotel with a picture of Mohsin Ghalain. The others were arrested in another hotel. All the defendants then disappeared from view until early January. The British Embassy in Sanaa was not told what had happened.
When Abu Hassan kidnapped the tourists it seemed like one more Yemeni kidnapping of foreigners of which there have been over a hundred cases. None had been killed or injured. He demanded the release of two well known Islamic dissidents, but not the five Britons arrested earlier. If these men were really an assault team of Abu Hassan's group it is strange that he did not ask for their freedom.
The police said they had found a grenade and explosives in the al-Wafa hotel as well as mines and two rockets in a car being used by the Britons. They produced a confession from Malik Nasser, since retracted, saying that Abu Hassan had given them an arsenal of weapons.
So far the Britons have only been charged in general terms with planning killing and explosions. Today their lawyer, Badr Basunaid, will ask for an adjournment to consider the detailed charges.
"There is a string connecting Abu Hamza to both the kidnappers and the men on trial," said one Yemeni observer. "The prosecution may be trying to turn it into a rope."