When Irfan Naseer and Irfan Khalid returned to Birmingham Airport from Pakistan in 2011 they were being watched closely by police.
They had travelled to the country to carrying out training in using bombs, poisons and guns. It was their second extended trip to Pakistan, visiting Waziristan - a mountainous province bordering Afghanistan with strong links to Al Qaeda and the Taliban.
Here the two men are seen being met by Rahin Ahmed, another man involved in the plot who has already pleaded guilty.
Another surveillance image shows them in the Birmingham Airport car park.
From this moment on West Midlands Police kept them, and Ashik Ali under close watch.
Covert bugs were placed in their cars and at Ali’s rented flat in Sparkhill, which the three men used as their base for plotting the attacks.
Officers heard the men experimenting with chemicals and discussing detailed formulas and methods for bomb making.
Police later found a partly burnt diagram containing what was described in court as ‘a blueprint for a viable home made explosive’.
In one of the covertly recorded conversations Irfan Naseer discussed how many people might be killed with a one kilogramme bomb, especially if nuts or nails were sellotaped to it.
– Irfan Naseer
"You probably kill about 25 people with a 1kg one"....probably injure about 60, 50…1kg is like the noise of about 50 bullets together. 7 or 8 of them in different places with timers on...to go boom boom boom everywhere."
One of their plans was to use chemicals from sports injury cool packs.
They were heard splitting a pack open and heating the material inside. The men had also discussed timing devices.