Following a reference to Pottertons in Ian Young's bulblog, I checked out their website. This year they were selling N. hedreanthus bulbs so I ordered three. Currently, there are six apparently separate plants emerged after about a month in the compost. So, I'm inclined to recommend Pottertons on that basis.
I rec'd 2 single bulbs, a double bulb and a very small bulblet, so six plants from those seems good value.
Jack