Wiper problems

I have a 300 series Discovery. When I turn the front screen wipers off, they take between 10 seconds and ten minutes to stop. This can be very anoying when its not raining? Doesn't matter if I use the quick wipe, intermittent or continuous, fast or slow, same problem. I've tried changing the relay in the footwell but to no avail. Any suggestions?

Dodgey stalk wiring/switch?

Trace the wires back, short the pins on the relays etc and see if switching the wipers on this way will turn off immediatly, then you know its the switch gear.

I have same thing on defender 200 TDi, but only on intermittant, assumed mine was capacitor discharge style intermittant control, if the screen is dry it stops quickly as the wipe takes longer, but keeps going if wet - pay a lot of money for sensing wipers in some vehicles!!!!!

Thanks fot the responses guys, I'll try the suggestions.

Could it be the self-park switch? Does anyone know where this is? Is it incorporated into the wiper motor?