When police stopped two cars on the M5 in the West Midlands they probably were not expecting to find 16 tightly-bound lambs, filling the boots, backseats and foot-wells.
It was another suspected case of sheep-rustling, a crime farmers say is on the increase as a result of rising meat prices.
Insurance firm NFU Mutual said it had seen a steep rise in claims for sheep theft. It estimates the cost of rustling to the industry had risen five-fold in a year - and is now costing UK farmers more than £5m a year.
Malcolm Roberts has doubled the size of the green dye markings he puts on sheep at his north Shropshire farm since losing 45 breeding ewes to rustlers.
He believes that although his animals were prime breeding ewes, they were soon slaughtered and sold on the black market.
"Considering the quality of these ewes - it's criminal. They were in the prime years of breeding as far as we were concerned, just three and four years old."
Mr Roberts, who lost the sheep just before the breeding season in August 2009, got about £120 an animal through his insurance.
"They had already weaned their lambs and ewes on their own tend to make no noise. If they had had lambs with them there would have been a lot of bleating involved," he said.
He said he now fed his flock in the middle of his fields to stop them hanging round gates where they would be easier prey for rustlers.
Martyn Leek, deputy editor of the Meat Trades Journal, said the average price producers got paid for lamb during 2010 was £3.81.5 a kilo - nearly 9% higher than in 2009.
"Recent harsh winters have contributed to lack of supply - and a lack of supply means higher prices.
"UK sheep meat is also an export success, which again impacts on the price here at home," he said.
Tim Price, NFU Mutual spokesman, said quite a few cases involved more than 50 sheep.
"We believe it is being done professionally because of the numbers involved and also because it is quite a difficult and complex operation for thieves," he said.
He said rustlers needed quite a lot of room to store or slaughter sheep and perhaps used dogs to round them up and vehicles to transport the livestock.
Mr Price said some animals were killed in fields or in "cruel and very unhygienic conditions".
He said some thieves could be forging documents to take stolen livestock to slaughterhouses.
Mr Price advised the public to be wary of buying meat from unusual sources, such as from pub car parks or through friends.
Police in Northumberland have stepped up patrols after a big increase in sheep rustling in the area. Officers said the value of animals stolen there had risen from £9,000 in 2008 to £39,000 last year.
In one incident in Ramsbottom, Bury, a flock of 271 sheep was stolen, worth up to £25,000.
On Dartmoor, about 370 Scottish blackface ewes were taken from moorland near Princetown over a six-month-period last year.
One Dartmoor farmer, John Heard, hit the headlines after responding to the problem by dyeing 250 of his blackface ewes orange to deter rustlers.
Mr Heard, who previously lost about 200 sheep from his farm, said the sheep's identifiable coats were proving to be a good deterrent.
The NFU said that as well as being financial burden for farmers, livestock thefts raised "huge questions over meat traceability and standards".
A spokesman said: "The NFU would urge people to continue to be vigilant in rural areas, join Farmwatch schemes and keep an eye out for suspicious people or vehicles.
"The rural community is close-knit and we would urge people to report anything unusual to the police."