from directgov:
Vehicle identification number - a vehicle identification number must be permanently displayed and legible on a vehicle first used on or after 1 August 1980
Registration plate - condition, security, legibility and format of letters/numbers
Lights - condition, operation, security and correct colour. The headlamps will also be checked to see if the aim is correct
Steering and suspension - correct condition and operation
Wipers and washers - operate to give the driver a clear view of the road
Windscreen - condition and drivers view of the road
Horn - correct operation and type
Seatbelts - all seatbelts installed are checked for type, condition, operation and security. All compulsory seatbelts must be in place
Seats - front seats secure. Front and rear backseats can be secured in the upright position
Fuel system - no leaks, fuel cap fastens correctly and seals securely. The fuel cap will need to be opened. Make sure the key is available
Exhaust emissions - vehicle meets the requirement for exhaust emission. These vary on the age and fuel type of the vehicle
Exhaust system - complete, secure, without serious leaks and silences effectively
Vehicle structure - free from excessive corrosion or damage in specific areas. No sharp edges
Doors - open and close. Latch securely in closed position. Front doors should open from inside and outside the vehicle. Rear doors may need to be opened to gain access to testable items
Mirrors - presence, condition and security
Wheels and tyres - condition, security, tyre size and type, and tread depth. Spare tyres are not tested
Brakes - condition, operation and performance (efficiency test). Suitable vehicles will be tested on a roller brake tester. Vehicles such as those with permanent 4-wheel drive will be tested either on a suitable road using a properly calibrated and maintained decelerometer or, if one is installed at the test station, a plate brake tester