Hi,
On a 210 the lamp out warning light comes on at the point the defective bulb is called upon to operate. If the warning light comes on with the first click of the light switch then it will be either the front side lights or one of the rear ones, second click will be one of the dipped beams, and if when operating the brakes then you guessed it one of the brake lights, the rear cluster bulb holders were known to overheat and melt on the 210, I would pretty much guarantee that your issue will be with one of the rear lights/brake lights being intermittent.
Check the bulbs/bulb holders, the bulbs should be under spring tension by the lower centre pin contact for the bulb, the bulb should be able to be pushed under this tension down in the bulb holder, what normally happens is the bulb holder gets hot and melts just enough to stick the bulb to it.
New rear cluster bulb holders are available from MB and are cheap, they were modified after a certain date in an attempt to compensate for this.
This age 210 I am reasonably sure the number plate lights were not on the lamp failure circuit.