Did you cut them back or did you let them die back naturally? Daffs need to build up a store of energy to flower the following year and they do this in the time after they have flowered so if you cut them back during this time they won't have stored enough energy to flower the following year. I feed mine on tomato feed during this time to help them.

Just make sure it is half strength tomato food. Otherwise Great is correct. Lifting an moving is not going to help.

No they were all left to die naturally, I wondered whether the cold winter affected them, if I feed the plants with no flowers will they flower next hear or shall I just buy new in September.

Feed them all now - this should mean they flower next year, unless the soil is too dry - watering will help, though I don't know what your rainfall's been like there - we haven't had any for over 3 weeks here in London, its beginning to resemble the Sahara desert...

Sjw cold shouldn't have affected them - we had far worse weather than you and although we have a few blind bulbs by far the majority are flowering away happily.

I think this came up on Gardener's Question Time a few weeks back, & they said to plant them deeper, so it might be worth lifting them when they have finished dying back & putting them back a bit deeper.

Also make sure they are getting at least 4 hours of direct sun each day. Too much shade can cause blind daffs--or any bulb.