The explosive - PETN - is used in detonator cord, John Bevan, QC, for the prosecution, said. He alleged IRA bombers chose a private spot on wasteland in Barking, east London - a half hour's drive from Docklands - to make final preparations for the blast, which claimed two lives.
"No sensible terrorist would wish to drive a lorryload of home-made explosives from Belfast to London with the bomb primed," Mr Bevan said.
"One would pick a convenient place near the final destination to perform the important task of linking the time and power unit [timing device] to the explosive," said Mr Bevan. "The wasteland would be an ideal and convenient place." When it reached Canary Wharf the clock would be set.
Patrick McKinley, 34, from Newry, and James McCardle, 29, from Crossmaglen, Northern Ireland, deny conspiring to cause an explosion likely to endanger life or cause serious injury to property in the United Kingdom or Ireland between 30 October 1995 and 10 February 1996.
Mr McCardle alone also denies murdering Inam Bashir and John Jeffries, whose newspaper stand was destroyed by the bomb on 9 February 1996.
Mr Bevan alleged that important evidence was found in the area where the trailer was abandoned. Swabs taken from the trailer showed the presence of PETN - a constituent of Semtex also used as an explosive filling for detonator cord.
"The presence of PETN on that trailer makes a clear and logical link to the bomb lorry," mr Bevan said. "The bombers had two jobs to do - to take off the trailer and arm the bomb.
"If they prepared the bomb first, dealing with the detonator cord, they got PETN on their hands or gloves and left it on the trailer, when they took the trailer off the lorry."
Motorway video surveillance footage from various cameras showed a "largish, ungainly looking vehicle transporter with a trailer on its back" had travelled on the motorway.
Tachographs recording the lorry's progress on the two days leading up to the bomb were also found at Barking. It had travelled from Stranraer to Carlisle on 7 February, Carlisle to South Mimms, Hertfordshire - stopping at a service station at Cannock, Staffordshire - on 8 February and from South Mimms to Barking and then South Quay, Docklands, on 9 February, he said.
The trial continues today.