Here we go again .....
RS Bikepaint will match the colour. I've had touch up sticks and aerosols for silver ST2, matt grey ST4s, dark blue M620, red 749S and all matched exactly. I resprayed parts of the metallic silver ST2 fairing and mirror after a spill instead of replacing it and it was unnoticable.
Get their number from their website at
http://www.motorbikepaint.co.uk They don't do Internet sales, prefer you to phone so they can discuss the right model/year/colour. Very helpful they are too.