I'd give them a good feed now then lift them at the point you'd remove the spent foliage. you wont compromise the roots that way.
if you lift them now the roots may not re-establish then they wont take up any nutrients.

That's what I thunked. Ta.

Did you cut back the foliage too soon last year, ie before it had fully died back as this is often the cause of 'blind' daffs.

No, definitely not. Never been known to cut back the foliage on anything.
Neighbour says that they were probably mown over in previous years, before we moved here.

Have you been pleasantly surprised by the previous owners plantings or not Owd?

Owd, can't you just give them a good foliar feed rather than replanting? Then a mulch as well at some point to improve the ground for next year? Foliar feed on its own worked on our wild bank where there are far too many to move .

SBG. There are few things left from previous owners plantings. There is a very nice Acer japonica, some Rhododendron Cunninghams White, a lot of Pheasant'sEye Daffs and a pink flowered Caryopteris. Otherwise either we have had to remove the plants or very ordinary things. We think (neighbour tells us) that they mainly had grass with bedding out borders.
Yorkslass. These would have been fed last year and are still not flowering . They are probably not in the best place either so moving them is best. We do need more Narcissus at the other end of the garden so they would have been moved even if they flowered.