The reason for the introduction of the Independent Driving Section in 2010 was to attempt to give the driving test more realism.
The DSA wants to encourage 'independent thinking' by getting the test candidate to show their skill level at doing an everyday section of driving.
Traditionally, the Examiner would guide the candidate for the whole of the test by giving directions.
With the addition of the independent section, the candidate has a chance to make decisions for themselves.
During the driving section of the practical test, the Examiner will ask the candidate to pull over.
The Examiner will then explain that the next section of the driving test will be done independently by the candidate, which basically means, without directional instructions for every route change.
Use of SatNav equipment is not allowed
There are different ways that they Examiner can ask the candidate to drive independently.
These are either:
Using road signs and markings
So they may say, "I want you to follow the sign posts and markings to the train station".
Using a series of verbal directions
So the Examiner will give instructions that includes a few different route changes - a bit like when someone explains how to get somewhere in a town you don't know.
...or a combination of both the methods above.
More Info: Independent Driving Section Example
The DSA states that this section is a test of independent driving and not a test of a candidate's map reading or memory skills.
Therefore, deviating from the route is not a problem as long as the drive in the wrong direction is competent and safe.. This basically means that your driving will be marked the same way as the rest of the driving test.
Getting lost during the independent drive
If the wrong route is taken, the Examiner will simply redirect the candidate back onto the test route, then the Independent Driving Section will continue.
Forgetting the directions during the independent drive
It's perfectly acceptable for a candidate to ask the Examiner for the directions again before or during the independent drive.
The Test Examiner will show a simple map of the route while giving the directions so that the candidate gets a mental image of the route.
More Info: Independent Driving Map Example
If, for any reason road signs and markings are obscured, covered or not easy to see, the Examiner will prompt the candidate through that section e.g. "there's a van parked in front of the signpost ahead, you should be turning left."