It's a lot less bovver with a hover, the slogan used to run, as lawnmower manufacturers fought to persuade a public torn between the conventional rotary lawnmower and its newer hover mower rival.

Black & Decker, which makes both types, says that each has strengths and weaknesses.

Rotary mowers, which have a single blade turning around a vertical axis, are excellent for grass pick-up ability and for mowing in straight lines, but are not easy to manoeuvre. Hover mowers, in contrast, are great for slopes and cutting near walls because of their good manoeuvrability, but their grass pick-up is less satisfactory. This is because it is difficult to use airflow simultaneously to keep the mower off the ground and to direct the grass cuttings.

Now, after four years of development, Black & Decker's European consumer products plant at Spennymoor, Co Durham has come up with the 4x4 - not an off-road vehicle but an independent four-wheel steering mower which combines the manoeuvrability of a hover with the efficiency of a traditional mower.

Initial market research suggested consumers wanted good manoeuvrability, good grass pickup and an easy means of height adjustment for different grass lengths. To try to meet these needs, Black & Decker has created a rotary mower mounted on four castors. On each castor are mounted two wheels which can rotate through 360 degrees - an idea which it believes to be revolutionary in the lawnmower world.

"You can turn it on a sixpence," says Mr Brian Cooke, director of engineering at Spennymoor. "When you want to go around a corner the wheels will move simultaneously."

Alternatively, the rear castors can be locked if the user wishes the 4x4 to mow in straight lines. Its height can also be adjusted.

The idea of castors rotating through 360 degrees sounds very simple but there were technical challenges, including the single knob height adjustment and the rear wheel-locking mechanism. Also, because the wheels need space to rotate, the mower's air flow had to be strong enough to lift the grass over the wheels to reach the box.

The 4x4, which has just entered commercial production at Spennymoor, comes in eight specifications, including cordless and corded models. Main markets will be the UK, continental Europe and Scandinavia.