Wow such a great respons. Thanks everybody.
I am still unsure whether to dig them up and discard them, mow them down or leave them all together?
The bulbs in a friends garden so when I am there I will dig some up and see how deeply they are planted. I believe they were planted long before the arrived there. So can not be sure on what type of daff they are unfortunately.
We are based in Farnham, Surrey. It has been quite mild with only a few hard frosts. It is very strange that they are at full height and I did notice just one flower bud on one of the stems, but this has happened for at least the last 2 years.
A little further down in the lawn there are more daffs that come up fine every year and flower beautifully. So maybe these ones just aren’t planted deep enough.
As for feeding. My Friend strongly believes in gardening the organic way so no feeding has be done as of yet ( a new topic I think as the lawn is more of a moss lawn, based on an acidic sandy soil and not knowing the best solution for the grass)
I will get back to this post once I have dug up some bulbs to see their size and depth but I think unfortunately the best remedy might be to remove them. Probably ruining the grass/moss in the process.