In Sadie's theory, at least 3 people would have been required - a watcher, an abductor & a getaway driver. A watcher would have had no quick route from the upper north balcony in Block 6 to the south car park. IMO.
Even * IF * there was no ultra quick way thru to the car parking area opposite the tapas reception, it would have been simplicity itself for The Watcher to exit via the front steps, turning right (east) and almost immeditely turn right again (south) down the alleyway that leads to the other end of that same little car park, which needed a third right turn.
If the getaway vehicle were parked at this eastern end of the car park, then it would be out of sight of the Tapas Reception and really very hidden ... Just another vehicle parked to the casual eye.
So, in some ways this route would be better to disguiise the Watcher and the vehicle
1) Vehicle tucked away, yet close and convenient ..... HIDDEN IN PLAIN SIGHT
2) Watcher exited the balcony and
walked away in the opposite direction to 5A ... so any one who saw him would not associate him with the goings on at 5A...... his actions effectively made his deeds be HIDDEN IN PLAIN SIGHT
He then turned a second corner, going right again, (south) into the first alleyway, before turning right for a third time and walking into the car park and climbing into the vehicle. Anyone seeing him come into the car parking area would see that he had NOT come from 5A direction, but from the opposite direction So once again his deeds were effectively HIDDEN IN PLAIN SIGHT
And the total distance that he would have walked from the bottom of the stairs to the getaway vehicle = 70 metresAchievable easily in just over a minute, probaly less for a younger man. Perfect tioming again to match the lifting and taking of Madeleine
AIMHO Just a theory