Parking in a car park bay, or bay parking. How to do it:
If you take a driving test at a test centre that doesn't have its own car park, the reverse into a bay currently won't be performed. The reverse into a bay currently isn't done at Clacton, or Brentwood. Although the new driving test from Dec 2017 will include bay parking, either reversing in, or reversing out, in various other car parks.
The examiner will give you the following instruction as you enter the test centre car park:
"I now want you reverse park into a car parking bay of your choice. Please treat the manoeuvre as if you are doing it in a busy supermarket car park."
The part about the busy supermarket car park means that your observation must be appropriate to a busy car park full of moving cars and pedestrians - not an empty test centre car park. The manoeuvre will always be done in the test centre car park. If your chosen test centre doesn't have a car park, you won't do this manoeuvre.
Remember you can shunt forwards at least twice to correct or re-align if you are unsure. If you do shunt make sure you go far enough forwards to make a difference.
You should be looking over your shoulder – out of the rear window at least half of the time when reversing. Take all round observation at all stop points.
If you reverse into a space on the right side then use the same technique but transpose left with right and vice versa.
To pass your test you can be on the line but not the other side of it, and you may finish at an angle as long as you are within the space.
Note: When you are parallel to the lines each side you will not look completely parallel in the side mirrors. This is because there is a distance perspective effect (like looking down a railway track that looks narrower in the distance). All you need to do to allow for this is to get the angles looking similar each side - your distance from the lines doesn't have to be the same both sides (photo below):