Are these the ones on the three dials for the heater controls Charles? If so make sure you get the correct wattage - 0.4W from memory - as otherwise they can overheat the plastic and melt it!
There are two types. 0.4w for the bulbs that illuminate the three rotary heating switches - available from the dealership plus 1.2w clear bulbs for behind the sliding heater blower switch (2 required) and one that illuminates the gear lever surround.
Don't use the 1.2w clear bulbs for the rotary switches as they get too hot.
Thanks all - I had a recollection from times past that it was an 0.4v bulb - the same as the W124, which of course I couldn't track down on-line. Time to say hi to the parts dept at MB Heathrow.