what was the actual plan of evans?[evans tries n o'level ]

Evans makes a very clever escape plan that he executes on the day he takes his O-level German test. The German teacher, the invigilator McLeery and a few other friends are accomplices in the plan. During the exam, a fake call is to be made to indirectly let Evans know the name of the hotel he is to go to as well as to let his co-conspirators know the time the examination is to end. After the exam ends, the invigilator is to exit with some visible change in his person to leave an impression that Evans has escaped in his disguise. Further on, the real Evans by that time would disguise himself as the 'real' McLeery and spill blood over himself. He would tell the police that Evans has escaped in his disguise after attacking him. He would claim to know the whereabouts of Evans and ask the police to drive to Elsfield Way. From there, he would leave on the pretext of taking an ambulance.