If they are in the ground zilch simply let them die back

dead head them and give them a feed to encourage the bulb to grow big and fat ready for next year. This is true if they are in a pot or in the ground. keep checking for lily beetle. [scarlet beetle adult. black slimy deposit under neath with a beige grub inside the larva, eggs about 1mm long reddy orange] remove all pests and squish.

And wear rubber gloves to do the squishing, they're disgusting creatures, Derek.

Thanks for that everybody, those comments are a big help, it sounds that I don't have to do much at all.
Thanks again,
Ian.