My interior bulbs seem to stay dimly lit when the light is not on, this includes whilst driving, and the car locked it doesn't happen if I move the switch to always off but in the middle position on the switch, I recently changed the bulbs from incandescent to LED

LEDs only require a very small amount of power, there must be enough residual power to illuminate them when they should be off. 

You can either fit CANbus ready LEDs or a resistor to each LED. Probably cheaper to get new LEDs though 

Fit a 10Kohm 1 Watt resistor and a 1N4004 diode in series with the supply wire to the light and it should fix the problem. If after fitting them the light won't work then the diode has been fitted the wrong way round.

I had the same problem on a Vauxhall Movano after changing the lamp to an LED

 

To be honest i was more worried about it running my batery down eventually but after looking at my car this morning the car's electronics shutdown while parked and locked seems to be working properly because the lights weren't lit when i went out to check keeping the doors locked. the lights are so dimly lit whilst driving that unless you look directly at the light you don't notice it as in its just bright enough to light the lense of the light

6 minutes ago, Neb_engineer said:

To be honest i was more worried about it running my batery down eventually but after looking at my car this morning the car's electronics shutdown while parked and locked seems to be working properly because the lights weren't lit when i went out to check keeping the doors locked. the lights are so dimly lit whilst driving that unless you look directly at the light you don't notice it as in its just bright enough to light the lense of the light

The amount of draw from the battery is negligible, it's highly unlikely to deplete your battery, but never say never 😉 it is a ford after all lol. 

Personally I'd want to try different LEDs because in comparison to a battery they are cheap as chips. You could use resistors and diodes but in my opinion it's a lot of hassle and probably more expensive than the LEDs you bought.

i mean there only 30 lumen bulbs