How MSPSL works:
Mirrors: Check your mirrors in good time to assess the position and speed of traffic behind you. Check that it is safe to carry out the manoeuvre.
Signal: Based on your observations consider whether a signal is necessary. If it is, signal your intention to change direction or speed in good time being careful not to mislead others.
Manoeuvre: This is broken down into the following steps:
Position: It is not always necessary to alter position of the vehicle, however, when a change of position is needed, move into position in plenty of time. This also helps to reinforce your signal and intent to others.
Speed/ gear: Once you have taken up your position, you need to make sure your speed is appropriate for carrying out the manoeuvre safely. Using the footbrake progressively gives you control and signals your intentions to others.
Gear: When the speed is right you need to consider selecting a gear which will allow you to maintain control of the vehicle throughout the manoeuvre and which is appropriate to the road and traffic conditions.
Look: You will of course be looking ahead and assessing throughout the routine on approach, but this is where the decision to proceed or wait has to be made. This part is broken into four deciding factors:
Look: What can you see?
Assess: Is it safe to proceed?
Decide: Based on what you can or can't see
Act: Wait or proceed.