HOW would you feel if a piece of disused land or a neglected urban space, such as a grass verge or roundabout, was suddenly made into a productive veg patch or pretty flower field?

Well, on the surface it might seem a no-brainer, but according to a recent study by university professor Peter Larkham, not everyone takes kindly to guerrilla gardeners cultivating land that they often do not have the legal right to use.

Professor Larkham has now written a book, Informal Urban Agriculture: The Secret Lives Of Guerrilla Gardeners (www.springer.com), in collaboration with his former PhD student Mike Hardman, in which they interview and observe groups of guerrilla gardeners in the Midlands, where a lively community has formed in recent years.

Professor Larkham, associate head of Birmingham City University's School of the Built Environment, says: "Guerrilla gardening is an international phenomenon. Those involved take part for a number of reasons, from brightening up their neighbourhoods to using gardening as a form of political protest.

"The land they are targeting is quite varied. It seem to range from traffic roundabouts and roadside grass verges to bits of land that one planner once called SLOP - Space Left Over after Planning - to derelict sites, unused patches of land which are clearly in somebody's ownership but aren't in any sort of productive use.

"In the book, we particularly focus on the guerrilla gardeners who plant edible crops, investigating the reasons why they get involved - for some, it is more 'naughtiness' than the wider public health benefits that could result."

He says it is not known how many guerrilla gardeners there are in this country - or how much land they cultivate - partly because the practice is illegal and partly because land ownership is so fragmented. But it has changed as social media has enabled individuals to link together to form small groups.

The reaction of landowners to these guerrilla gardeners is usually negative, he observes.

"They don't like their land being interfered with. What the guerrillas do can be quite varied. Some of them just want places to look a little nicer, so they just scatter flower seeds. In one famous case in New York, guerrillas threw bundles of flower seeds over fences into unused patches of land and called it 'flower bombing'.

"Others go on to the land and clear it, cultivate it and grow either flowers or productive crops. It's the trespass which landowners don't like."

However, some communities have come together through guerrilla gardening, he says.

"Look around our towns and cities and there's a massive amount of unused land which could be used. Our research was looking at what happens to these guerrillas once they've made their point. Do they start looking for land they could cultivate legally? I suspect that's the future, that guerrilla gardening is part of a wider urban agriculture movement."

The research found that the impact of guerrilla gardening on communities was mixed.

"A small number were negative. They weren't consulted. They felt aggrieved that it was being done on land adjacent to their property. But the majority were very supportive. They could see the change being positive, the land being used, being looked after a bit more."

There are some areas where guerrilla gardening has really taken root and inspired and brought together the community, such as Todmorden, in Calderdale, West Yorkshire.

"A small-scale guerrilla gardening movement was looking to make prettier what was a small industrial town. That grabbed everybody's consciousness and the movement took off, legal sites were found and it's really at the forefront of a legal urban agriculture movement which now comes under the label 'Incredible edible Todmorden'.

"It's made a significant difference, particularly in summer when the plants and the crops are much more visible. The place is greener, more interesting and is helping a lot in building a community response as to what sort of opportunity we can make of derelict patches of land.

"When the council found it was a positive thing rather than purely a case of illegal trespass, they got behind it.

"Other places are supporting legal urban agriculture. A lot of local authorities are taking notice, partly because of concern for food security and also because of big agendas for health and wellbeing. Agriculture provides both psychological and physical wellbeing, although urban agriculture is probably more important for building communities and promoting healthier lifestyles than for producing large amounts of crops."