This gets even stranger now!
Many thanks guys, but after changing the function to DrAzzy's suggestion, the led still stays on until a second push of the switch when it will extinguish then immediately ramp up to what looks to be the brightness = 100 level and then extinguish completely without ever coming on full. Subsequent switch presses repeat the same sequence.
I'm also suspecting my switch operating function is faulty now as it was supposed to trigger on state change, but it seemingly is now repeating itself if held down.
I must admit that I was following the reasoning, but this doesn't seem to make sense now!
Bernie