Features to consider

Body
A rotary mower’s body is made from steel, aluminium alloy or (less commonly) plastic.

An alloy body is more expensive. It’s corrosion resistant and likely to last longer in damp conditions – although it won’t last as well in sandy coastal areas because sand wears away the aluminium.

Steel is cheaper but will rust unless cleaned and dried after use. However, if hit by a large rock it’ll only dent – whereas an alloy body can crack.

Plastic is lightweight and doesn't corrode … but it may not last as well if regularly pounded by stones and other debris. A plastic body is more suitable for well-tended lawns where there’s only a slight chance of it being hit by rocks or stones.

Handle
A turned-up handle is generally regarded as easiest to use. Adjustable height is also an advantage, although it's not as common as you might think. The handles should fold easily for stowing.

Throttle control
Located on the handle bar for quick and easy access. It shouldn't be stiff.

Cutting height
Look for a large number of cutting positions. It should be easy to change the position using one lever acting on all four wheels.

Catcher
Catchers can be either solid plastic or partly mesh. Rigid plastic is heavier, but stronger than the mesh type, which can allow dust to blow over the user. The catcher should have two handles, one for carrying and the other for emptying. It should be easy to remove and replace.

Engine maintenance
How easy will it be to change the oil, air filter and spark plug?

Starter cord
Some mowers have the starter cord on the handle, so you use just your arm and perhaps upper body to operate it. Others have the cord down on the engine casing, requiring a full body pull. Neither guarantees an easy start, and both have their fans. If you're not familiar with either style, ask to try it in the shop.

Some cords are located on the upper handle, which restricts the pulling action more than those placed further down the handle. Left-handers may find it harder to use a starter cord on the handle.

Wash port
Look for a hole on top of the body, designed for you to connect a hose to, for easy cleaning underneath

Noise
There's no such thing as a quiet petrol-driven mower, but some are noisier than others. Check the vibration as well.

Easy push
Ball-bearing wheels make pushing easier.