In my experience the most common reason people fail their test are:

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• Hazard awareness - Not spotting a situation starting to develop and not responding to other road users in a safe manner

• The Mirror Signal Manoeuvre routine - Not checking mirrors when slowing down, speeding up or changing direction. Not signalling in time or signalling too early

• Approaching junctions and roundabouts - Approaching a junction too fast, getting in the wrong lane or changing lanes without checking it is safe.

• Traffic signs - Not responding correctly yo road signs or makings such as getting into a bus lane or not stopping at a stop sign.

• Changing gear - Not changing up or down gear when necessary causing the car to increase or decrease speed rapidly or even stalling the engine in an unsafe position.

• Speed - Not using appropriate speed for the conditions of the road or exceeding posted speed limits. Not making reasonable progress when it is safe to do so.

• Emergency Stop - Failing to stop promptly or not make safe observations when moving off.

• Parallel parking - Mounting the kerb, clipping parked cars or failing to observe correctly.