Yellow Star of Bethlehem (Gagea lutea) - Why so few flowers?

It was the annual count yesterday of flowers of Yellow Star of Bethlehem (Gagea lutea) at Whitehill Wood by the River Evenlode.  A week earlier than last year after a cold Spring, there were no violets, primroses and Wood Anemone just emerging, and too early for toothwort.  We found only one flowering plant of G. lutea, with a few more in bud, a total of nine plants, I think, and fewer than the average for the last 7 years, 13 flowering plants.   We did not rediscover two plants seen in flower earlier in the week; maybe they were chewed off by deer, of which there are lots in the wood.

What is remarkable is how few plants flower.   There are hundreds of non flowering plants, which are distinguishable in leaf, with some experience, from bluebells by the single, hooded basal leaf with a "long, inrolled apex" (Poland and Clement).   I counted plants in a 5m strip on each side of the path (5.5m x 0.4m on the river side, 5.5m x 1m on the other side, a sloping bank), a repeat of last year.

River:  53 non-flowering, 0 flowering (20/0 last year)
Sloping bank:   40 non-flowering, 0 flowering (43/1 last year).

The percentage of flowering plants is tiny, but why?   Do the plants not develop enough once they have germinated to produce a flourishing plant or do they spread vegetatively, (but in that case there would be tight clusters which is not the case)?  It does of course 

Most plants were juveniles, but a few looked robust enough to bear flowers. In the wood above, which slopes quite steeply, there were plenty of leaves but no flowers.  This is replicated elsewhere and also seems to be consistent with the genus.   I remember from visiting years ago that it was also true of G. bohemica in Radnorshire - lots of plants but very few flowers.   

I have looked at the dataset and can find no reliable correlation with climate, other than a very wet June / July in 2012 was it seems linked to no flowers appearing in 2013.

They seem to prefer minimal competition.   There are none where ransoms grow, and tail off where the dog's mercury takes over.   

The one flowering plant faced the river at a point which was deeper than the height of my wellingtons, and the resulting wet feet in slippery mud might offer an excuse for these slightly out of focus pictures.