In the garden I leave them until the leaves and stems have died off, then cut the dead stems just above ground level. Nothing else.
In pots I again leave them until the stems have died, cut the dead stems and then repot them in fresh compost.

Can I join in please? When would be a good time to move them if they are planted in the wrong place?

Immediately before they finally die off for the year, Steragram; whilst you can still see where they are. They can be moved after this but I would either not be able to find them or else forget all about them until they grew in the wrong place again next year :-)))). Unlike daffodills or crocus, lily bulbs never really go dormant so should be treated like plants and replanted again asap. Don't trim off any roots below the bulbs, these don't die off and should be kept complete.

Thank you very much! I will try to be careful with those roots.

Mine wasn't grown from a bulb. I bought it from the GC as a plant. Is the advice the same please. I've just moved mine.

I've been wondering if certain varieties flower longer as I see the big ones are still for sale in the GC. Mine stopped flowering in end of June.

Just the same, Annelise, it will still be a bulb even though it was growing when you bought it. Different species/varieties of lily flower at different times of the summer. We have lilies that were over by the end of June and others that won't start into flower until August. Lilies are wonderful plants to grow and we have quite a range of them.

Please can I join in as well? Do you think it is better to grow lilies in the ground or in pots, Bulba, and what is then best position for them?

Wow, all these questions, lol.
Some of the dwarfer lilies can readily be grown in pots but the taller ones, 1 to 2m, need the bulbs planting deeply at six to eight inches. Pots will rarely provide the support needed. Lilies like cool feet but the flowers in the sun. In the wild they often grow amongst shrubs with the flowers rising above the foliage. Thus the taller ones often have remarkably thin stems and need to be planted out of the wind or given some support - unless you plant them beneath shrubs, of course.

Thank you so much for that info, Bulba! I gaily buy pots of liles from the GC, but don't really know what to do with them afterwards. I shall have a think, now...

Bulba - what ones do you have that flower in August?

July is the main month for our lilies, Annelise. Flowering now, and will still be in August are Lilium lankongense, L. duchartrei, L. regal, L. nepalense and L. davidii willmottiae. In bud ready for August are Lilium lancifolium,L. lancifolium flaviflorum and one labelled L. citronella but isn’t! Most of these are the 'turks cap' type of lily.