A contractor employee was working from mobile scaffolding to repair a Portacabin. When he climbed down the side of the scaffolding it topppled over and strcuk him. He received injuries to his pelvis his back and to his lower abdomen. The scaffolding was placed on top of a narrow walkway and a wheel slid off when the employee was descending the ladder. The scaffolding was not inspected after the it was transferred to the new position and the labelling was not to PDO Standards.