Many thanks, Darren.
That's very encouraging. It does seem that my bulbs aren't old enough. Also, I think I'll leave the N.v. pots on the cill of a south facing window next year. They obviously didn't get hot enough in the sun outside this year.
I'll certainly re-pot them next year making sure the bulbs are not too deep. Maybe, I'll also top dress the compost with ground up house coal instead of grit. That would absorb the heat of the sun. Just a thought.
Thanks again,
Jack