Thanks for that James.
Have used this transistor with another 9v circuit, running pwm with no resistor.
Duly noted, if using as a switch - need resistor. (With calc used above)
Used a 1R2 (instead of 2150 ohms) resistor for a test and it held it open and then faded out. So i think i need to do some googling to further my knowledge.
Thanks for the help.