The bulb was labelled "Lilium moorei Album" (sic). Until just a few weeks ago it appeared to be rotting and it was about to be sent to the compost heap. Then it suddenly sent up some leaves with broken tips, followed by a stalk, and a delicate arrangement of long, thin flower buds. And this morning I found I had a Crinum amoenum (a bit distorted in the photo re-size, sorry).