They need to be planted in cactus compost so you will need to un-pot and repot also make sure the container is small enough cacti do not like to be confined.

It sounds as though they're not having enough light. They also need to be kept dryish and cool in winter.
I pot mine in potting compost with plenty of coarse grit mixed in. Clay isn't a good thing to grow them in.

I would put them in a slightly larger container to leave room for growth, and use cactus compost.It is aailable in quite small bags. Do this asap and water hardly at all over the winter. You can give them one good soak when the weather begins to warm up and you may find that flower buds appear almost immediately.

Thank you all for your advice. I shall put this into effect straight away.

Kind regards
Roberta Redemer

From my experience, though, the primary problem is not enough light. Since the top growth is now adapted to shade, you will need to increase the light gradually over a period of several months, or the tops will get a white sunburn, followed by tan, corky scarring. If they are hardened off again correctly, the tops will expand again, but those stems will always have a "waist" like a peanut. Offsets should be normal, though.

Thanks Tugbrethil for your comments. The cacti have been in a light room but not in direct sunlight, so I shall put them nearer the light gradually.
Regards
R Redemer

Since the human eye adjusts to light levels, it makes an unreliable light meter. Rooms that seem bright and cheerful to most people have often killed plants through starvation. : )

In Britain the sun isn't strong enough to burn them, especially in winter, so I think you could put them in direct sunlight straight away. Maybe you could give them some shade on a hot summer's day, but our weak winter sun won't burn them at all.

True! I didn't think about the difference in intensity of the sun between here and the UK!

An afterthought - it is often a good idea to put a little top dressing of coarse grit over the compost around the plant. This keeps the plant body dry and helps to avoid rot if conditions are accidentally rather too damp for too long, and it also helps to keep the plant free from bits of compost which can be quite difficult to remove without damaging the plant. And it looks decorative.

Update:

I have re-potted as suggested and put them in direct sunlight, and they have immediately started growing the white spines over the new green growth.

Thank you all for your help.

Kind regards

Excellent! Spines are the first thing to recover. : )