Erol Incedal, formerly known in the case as AB, is on trial at the Old Bailey accused of preparing acts of terrorism and possessing a document entitled Bomb Making on an memory card.
The 26 year old from London denies the charges.
Prosecutor Richard Whittam QC, opening the trial which will mainly be heard in secret, told jurors Incedal was stopped on September 30, 2013, for a road traffic offence.
Inside the black Mercedes he was travelling in police found a number of items including a piece of paper with the address of a property owned by the Blairs on it. It was found inside Incedal’s glasses case, the court heard.
Mr Whittam said: “Count 1 does not suggest that Erol Incedal had settled on a specific target or a particular methodology but in the context of the case as a whole and the evidence that I am going to come to, you may think that this address does have some significance.”
During the search, a listening device was put in the car, the court heard.