1997 disco 300tdi not switching off

as stated above, engine is not shutting down when turning ignition off and removing key from ignition, just keeps running, have searched the net already, i can confirm its not running on its own oil. i cant confirm wether its the stop solenoid or not.
i know i have a slight electrical error as i changed a brake bulb and put in a single filament bulb when it should have been a double filament which has caused the headlights to come on when the brake pedal is pressed.
is the brake bulb a likely cause or should i be looking more into the stop solonoid or ignition?
i'm a noob at repairs on cars so nothing too technical please
thanks

this may help you
http://www.landyzone.co.uk/lz/f8/my-engine-wont-stop-83140-2.html

stop solenoid

Try pulling the wire off the back of the fuel solenoid, this will illuminate either ignition or fuel solenoid. If it keeps running when wire is removed, it's the solenoid, if it stops when wire is removed, test to see if there's a 12v feed to the wire, this would indicate ignition.

it was the brake light, just went out and stuck a double filament in and its fine now!!! and it also fixed the problem of eadlights coming on when brake pedal pressed!! thanks guys. if the problem comes back then i'll get someone to check the solenoids.

Cannot believe this is all caused by a brake light bulb-personally I would be checking the earths are ok-hope I am wrong,but I don't think we have heard the last of this

stick it in 1st, put the hand brake on and lift the clutch....problem solved!

Be a lot smoother in fifth ... and kinder on the clutch, gearbox and engine ...

I had this problem after replacing the light stalk behind the steering wheel... happened once, stalled it to cut it out, left it for ten minutes started it up and never had a problem since... :confused2: baffles me but all the time its not causing me an issue I ain't gonna do diggin to find one!!!

all my probs like this were related to rear bulbs