The 73-mile long Roman wall, built in AD 122 to defend the Roman Empire from hostile Celtic tribes, created a thriving economy to serve the occupying army, according to aerial surveys.

Farmers, traders, craftsmen, labourers and prostitutes seized the occasion to make money from the presence of hundreds of Roman troops.

"Some of the local population will have seen the opportunity presented by the occupying forces and gone for it," said David MacLeod, of English Heritage. "There are entrepreneurs in every society ready to go for the main chance."

The research carried out by English Heritage has revealed over 2,700 previously unrecorded historic features, including prehistoric burial mounds and first century farmsteads, medieval sheep farms, 19th century lead mines and even a WWII gun battery, sited along the 15 foot high wall which stretched from Wallsend on the English east coast to Bowness-on-Solway on the west coast.

The study, based on over 30,000 aerial photographs taken over the last 60 years, offers an insight into the impact of the wall on the area's history and landscape.

Among the most startling discoveries are dozens of Roman-era farms and settlements strung out along a 15 mile corridor either side of the 10ft thick wall.

Instead of being wiped out by the Romans, the local population appears to have flourished as part of a booming military economy.

One farm trapped between the new wall and the gigantic defensive earthworks built by the Romans appears to have adapted to its new surroundings – much like a modern farm stuck between two motorways.

Other aerial shots show significant settlements next to the wall's military forts at sites such as Chesters and Housesteads – suggesting the presence of a large civilian population providing services to the Roman legionnaires and officers.

Mr MacLeod, senior investigator for English Heritage's aerial survey and investigating team, said: "Having got over the first shock of the invasion and occupation the native population began to see the potential created by the presence of the Roman garrison.

"The building of the wall appears to have provided a boost to the local economy. A sophisticated network seems to have grown up to supply the new market created by the occupation."

He said the survey found photographic evidence of several farmsteads and field networks on either side of the wall which would have adapted themselves to supply crops, livestock and other raw materials, such as leather, to the Romans.

Mr MacLeod added: "The Romans preferred to pacify the natives without resorting to violence, as its military force was dependent on the local population to provide it with goods and services.

"Every Roman fort along the wall attracted a motley collection of people selling food, alcohol and crafts, as well as labourers and even prostitutes."

The arrival of the Romans in the north of England would have also led to an influx of new consumer goods, with wine, olive oil, new types of jewellery and glassware made available to the local population for the first time.

"The locals would have had to pay taxes, but there must have been substantial economic benefits going both ways," said Mr MacLeod.

The aerial survey has emphasised the uniqueness of Hadrian's Wall and drawn attention to the wealth of human activity in the region which preceded the arrival of the Romans and continued after their departure.

At Errington Hill Head, near Hexham, the corduroy patterns of Medieval field cultivation are visible from the air, lying beneath a landscape now used as pasture, while earthwork remains show the outline of the Medieval manor and village of Ingoe, Northumberland.

Mr MacLeod said: "We need to remember that Hadrian's Wall is not an isolated monument set within a landscape devoid of any other history. This region saw a tremendous amount of activity before the Romans arrived and after they left, traces of which remain today."

One of the most vivid aerial shots, taken by the RAF in August 1945, shows an anti-aircraft gun battery defending nearby shipyards from German bombardment. Close inspection reveals that close to the guns was a baseball diamond, signalling the presence of a more recent foreign army in the shadow of Hadrian's Wall.