John Nutting, for the prosecution, told the jury that the map discovered at the home of Vincent Wood, in Leytonstone, east London, was a street plan of Huntingdon and Godmanchester in Cambridgeshire on which an area in the village of Stukeley - the home of Mr Major - had been marked.
Also written on the map was a figure 6, which Mr Nutting suggested could refer to the fact that the Prime Minister's home was almost exactly six-tenths of a mile from the nearest reference point, a roundabout on the outskirts of Huntingdon.
Mr Nutting alleged that when police raided Mr Wood's home, they smelt burning and went into the garden. In a dustbin, he said, they discovered the charred remains of the map in a bin liner. In Mr Wood's briefcase, they found the telephone numbers of two Huntingdon public houses, written in Gaelic.
Mr Wood, 29, a sales executive, denies conspiracy to cause explosions and possession of explosions with intent to endanger life between January and October last year. He had pleaded guilty to possession of explosives without lawful object.
The court heard that in early October 1992, Mr Wood had asked Tony Robinson, a friend, if he could leave a tea chest at his workplace in Goodmayes, east London.
After several days, two business partners of Mr Robinson became curious about the chest and opened it; with Mr Robinson they examined the contents and became suspicious. They contacted police who placed Mr Wood under surveillance on his return from a business trip to Ireland.
The tea chest contained 17.5 kilograms of Semtex explosive and five timing and power devices used to detonate bombs; three of them had the capacity to time explosions for up to 12 hours.
Mr Nutting said: 'To anyone who has ever dealt with explosions or anyone who has ever encountered objects left by the Provisional IRA to cause explosions, these objects have a dread familiarity.'
The issue before the jury was not whether Mr Wood had the articles in his control, but the purpose for which they were being safeguarded, he said.
After about 10 days, police decided to move in on Mr Wood because of an incident at his office in south London. While Mr Wood was away from his desk, a colleague had taken a call from a man with an Irish accent. When the man rang again, Mr Wood was overhead speaking to him with an Irish accent, a manner he often adopted when dealing with Irishmen, Mr Nutting said.
Although Mr Wood was born and lived in London, he had taken a deep interest in Ireland and Irish affairs. He was learning Gaelic and in 1990 married an Irish woman, a sister at a London hospital. But he said Wood had never been heard to openly support the use of violence. The trial was adjourned until today.