There was still a lot to prepare in a short time. All paratroopers, who were in hiding at various addresses, had to be warned in time and taken to the rallying point near Renkum. Also reconnaissance had to be carried out towards the crossing point, where the short cut ran across the German lines. This crossing was only a few kilometres away from the rallying point. In addition, the escape plan had to be coordinated with the relief troops on the south bank of the river. Finally, additional weapons and uniforms had to be dropped, so the paratroopers, if they would be discovered, could fight their way to the Rhine.
At the last meeting between the staff officers at the hiding place of general Lathbury, the agreement had been made that the escape route to the Rhine would be explored by major Allison Digby Tatham-Warter and a resistance guide. The transport company of Albert Horstman, would fulfil a crucial function during Operation Pegasus 1. He and his men were to transport sixty paratroopers to the rally with two small trucks, provided with gas generators. This was the most risky part of the operation, because these simple cars were not suited for off-road driving. Under leadership of major Tony Hibbert, the largest group of parachutists was brought together in a shelter in Oud Reemst, a small town near Ede.
The technical condition of the two small trucks of Albert Horstman was crucial to the success of Operation Pegasus 1. Two days prior to the start of the mass escape, two mechanics were constantly working on the gas generators of the little trucks, to have them completely in good condition. During the ride to the rallying point, nothing should go wrong with these failure-prone engines.
The leaders of the local resistance group were not allowed to neglect any detail during all preparations. There were one hundred forty lunches to be prepared and to be taken to the rallying point near Renkum. Reliable, patriotic doctors were deployed to medically assist sick and / or injured paratroopers, before they would make the crossing. Next to that, uniforms, weapons and ammunition had to be taken from the storehouses of the local resistance to the rallying point. Boys and girls from the local resistance were committed to guide the paratroopers, as inconspicuous as possible, to the rallying point.
On Friday, the 20th of October, 1944 a German car with a loudspeaker on the roof was driving through the streets of the town of Bennekom. Through the speaker, residents were told to leave Bennekom compulsory before Sunday, October 22nd. No reason was mentioned by the Germans for the forced evacuation, but the message led to great confusion and anxiety among the villagers. However, for a small group this German order was if it had been sent for. On October 21st and 22nd, due to this evacuation, roads would be very crowded, causing the Germans being unable to check the big flow of people. Local resistance considered this to be an excellent opportunity and therefore did not hesitate to make use of it. Due to this all, Operation Pegasus 1 had to be antedated by one day, which put extra strain on the improvisation abilities of the resistance.
Pieter de Kruijff and Albert Horstman decided to use trucks of the transport company, provided with the Red Cross logo, for Operation Pegasus 1. With these trucks it would be possible to transport a large group of paratroopers in one time, in a rather inconspicuous manner. In addition, the resistance would have more time and manpower available to guide other paratroopers to the rallying point near Renkum. A difficulty was that the trucks of the Red Cross, according the Geneva Conventions, were not allowed to be used for the transportation of armed paratroopers. Horstman and De Kruijff decided to assign two members of the resistance group of Horstman to be the drivers of the trucks. These two resistance men were not to know what the real purpose of the trip would be. During the trip, the two trucks would be 'raided' by the resistance near the village of Oud Reemst. This was close to where about fifty paratroopers were hiding and who then rapidly could jump into the trucks. Every few miles, female couriers would be standing along the road with a bicycle in their hand. If everything would be OK, they would be standing in the longitudinal direction of the road. However, if something would be wrong, they would stand across the road and pretend to repair their bicycle.