European Law now states that all light passenger vehicles registered on or after 1st August 1998 require a type approved towbar tested to EC94/20 and towball with suitable D&S value.
Fitting of a non type approved towbar on a vehicle registered on or after 1st August 1998 could result in prosecution and in the event of an accident, the vehicles insurance could be invalidated.
A car that has EC Whole Vehicle Type Approval (ECWVTA) will have a vehicle identification number plate (VIN plate) bearing the vehicle manufacturers name, chassis number and an approval number including the letter 'e' in a small rectangle. This plate is usually located under the cars bonnet but it can sometimes be located in other positions, for example, near the drivers door.
If you passed your driving test after 1st January 1997, then you will have restrictions on what you can tow.
If you are in doubt, please refer to the DVLA website.