[Mike_Brace]

The 200 series do NOT benefit with any plug in point for towbar electrics.
I always run the 7 core to the fuse box area:
Connections are as follows:

Black wire - fuse 9 (left side lights)
Blue wire - fuse 14 (fog lights)
Brown wire - fuse 16 (right side lights)
White - earth connection
Red - extend this to the brake light switch (on pedal mechanism) and connect to the wire which comes live when pedal is depressed.
Yellow and red - I extend these with a two core cable to the column indicator switch and connect in - determining with test lamp which wire for which side on switch - yellow is left indicator, Green in right indicator.
This method ensures the bulb failure lights works without any problems when trailer electrics are in use.

Mike