It stays in the wall when the screw is removed, so the fixing point is permanent.

A classic spring toggle loses its wings into the cavity the moment the bolt is withdrawn. A hollow-wall anchor's collapsed sleeve is clamped to the board and stays there.

That makes it the better choice for anything removed and refitted - shelving, panels, brackets, fittings that come off for decorating.

It is also easier to fit into an existing fixture, since the anchor is set first and the screw goes in afterwards.

The trade-off is capacity: the mushroom bears on a smaller area than a toggle wing.

Where the item never comes off and the load is high, a toggle is the stronger answer.

Because the legs are designed to buckle over a stated grip range, and outside it they do not form the mushroom correctly.

Too thick a board and the anchor closes before reaching the back face, so it clamps nothing.

Too thin and the anchor over-collapses, deforming past its intended shape and sometimes pulling into the board.

Grip range is printed on the packaging and is the main selection criterion after hole diameter.

Double-boarded partitions and boards with a skim coat are thicker than expected, so measuring rather than assuming is worthwhile.

Where thickness is unknown, a short length of wire hooked through the hole gives the answer in seconds.

It is much better with one - driving the screw to set the anchor is where most problems start.

A setting tool grips the anchor's flange and pulls the internal mandrel, forming the mushroom without turning the sleeve.

Setting by screwdriver relies on friction between the flange and the board to stop the sleeve rotating, and if it slips the anchor spins uselessly.

A spinning anchor cannot be tightened and cannot be removed easily, which is why they acquire a reputation for being fiddly.

Flange teeth help. Tapping the anchor lightly so the teeth bite the board face before setting greatly improves the odds.

For occasional use a screwdriver will work in sound board; for volume work the tool pays for itself quickly.

Pull outwards on the screw while turning, and if it still spins the anchor has to come out.

Tension on the screw presses the flange teeth into the board face, which is often enough to stop rotation and complete the set.

If the sleeve is already partly collapsed and spinning, it will not set correctly however long it is turned.

Removal is by drilling out the flange with a bit the size of the sleeve, then pushing the remains into the cavity.

A new fixing needs a fresh position, since the original hole will have been enlarged by the spinning.

Nine times in ten the hole was drilled oversize, so checking the bit against the stated size prevents a repeat.

For light fittings only, and never for anything whose failure would matter.

Overhead fixings carry sustained tension for their whole life, which is the least favourable direction for any plasterboard anchor.

The board itself is the limiting element, and board in tension around a small mushroom is weak.

Ceiling boards are also often thinner than wall boards and may carry insulation weight already.

Anything of consequence overhead should be fixed to the joists or to a noggin added between them.

Where a light fitting must go between joists, a proprietary ceiling fixing designed for the purpose is preferable to a general anchor.

Drill out the flange and push the body through into the cavity - it is not a tidy operation but it is predictable.

The flange is the only part holding the anchor at the face, so removing it releases everything.

Use a bit matched to the sleeve diameter so the surrounding board is not enlarged more than necessary.

The collapsed body drops into the cavity, where it stays; it cannot be retrieved and does no harm.

The resulting hole is the sleeve diameter and is easy to fill and redecorate.

Trying to unscrew the whole anchor rarely works, because the mushroom is a permanent deformation.

They can be, and where moisture is expected a stainless or all-plastic alternative is the safer choice.

Ordinary plated steel sleeves corrode in a damp cavity, and rust staining can appear through the board face.

Bathrooms, kitchens and utility areas are the common cases, particularly where moisture-resistant board has been used precisely because damp is expected.

Stainless versions exist and cost more; plastic hollow-wall anchors avoid the issue entirely at lower capacity.

The screw matters as much as the anchor, since it is exposed at the face.

In genuinely wet areas, fixing to the structure behind the board removes the question altogether.