Kafeel Ahmed sent his brother an e-mail two days before he tried to blow up Glasgow airport, telling him that he was prepared for the long haul but wanted Allah to protect him from going to the “dreaded prison”.

Sabeel Ahmed, 26, had a text message from his brother just before the attack, telling him to read the e-mail, which he did later. But he did not tell the police, and Friday he pleaded guilty to withholding information about the attack.

Kafeel, who had a PhD in engineering, instructed him in the e-mail not to tell anyone and to maintain a cover story that he was in Iceland on a global warming project. The message said: “My sincere request that you do the following: 1. Pray to Allah for acceptance of my deeds. 2. Pray to Allah to give you calm and composure and strength (for you will need this) 3. Do not inform anyone about me or my deed (and I mean anyone). 4. If they figure out it was me (I have tried to clear up my tracks as much as possible) then go ahead and tell them whatever they ask of you.

"And of course this is going to put you in trouble (Allah forbid). Say only that which is necessary. And please don’t argue. Try to continue as normal but appear shocked. Try to put off telling Abbu-Ammi [mother and father] for as long as possible. I am sorry for putting you in this situation. 5. If they can’t figure out who it was, then keep me alive for as long as possible. 6. If I am caught, then try to maintain calmness and don’t try too hard to get me released. I am prepared for the long haul (May Allah save me from the dreaded prisons).”

He adds: “Please take care of Abbu and Ammi. At any time, don’t hold back from joining the Jihad, by money, words and actions. Allah makes it easy for those who do so.”

He ends the e-mail: “May Allah . . . reward you for the troubles.”