Cannabis is known to leave its smokers feeling woolly-headed, but it seemed to have little effect on a flock of sheep who chomped their way through thousands of pounds worth of the drug.

The hungry hash-eaters came across seven black bags containing the class B banned substance that had been dumped at the edge of their farm in Merstham, Surrey, and started scoffing.

The fly-tipped plants, each about three-foot tall, had an estimated street value of £4,000 – police have just revealed.

Fanny’s Farm shop manager Nellie Budd told the Surrey Mirror: “My sheep weren't quite on their backs with legs in the air but they probably had the munchies.

”They haven't had any other side effects but I'll tell you about the meat next week.“

Recalling the incident, on Thursday, September 28, she said: ”My sheep being inquisitive had an interesting feast on it.

First legal cannabis sales in Washington Show all 10 1 /10 First legal cannabis sales in Washington First legal cannabis sales in Washington Washington's cannabis stores Kevin Nelson, of Bellingham, Wash., holds a sign that reads "Drug War Ends Here," outside Top Shelf Cannabis, Tuesday, July 8, 2014, in Bellingham, Wash. on the first day of legal pot sales in the state. Nelson says he is a long-time activist opposing drug laws, particularly those targeting marijuana users, and he he feels the legalization of marijuana will lead to less crowded jails and be less of a burden on the court system. AP Photo/Ted S. Warren First legal cannabis sales in Washington Washington's cannabis stores A pamphlet titled "Marijuana Use in Washington State," is displayed at the Cannabis City recreational marijuana shop in Seattle. The store will be the first and only store in Seattle to initially sell recreational marijuana when legal sales begin on Tuesday, 8 July, 2014. AP Photo/Ted S. Warren First legal cannabis sales in Washington Washington's cannabis stores Customers shop for marijuana at Top Shelf Cannabis, a retail marijuana store. Top Shelf Cannabis was the first retail marijuana store to open today in Washington state, nearly a year and a half after the state's voters chose to legalize marijuana. David Ryder/Getty Images First legal cannabis sales in Washington Washington's cannabis stores Cale Holdsworth, in town from Kansas to visit family, celebrates after purchasing two grams of marijuana strain "OG's Pearl" for $26.50 at Top Shelf Cannabis, a retail marijuana store David Ryder/Getty Images First legal cannabis sales in Washington Washington's cannabis stores A sign noting the Washington state law that prohibits opening packages that contain marijuana or marijuana-infused products in public rests on a glass case displaying bongs for sale at the recreational marijuana store Cannabis City AP Photo/Ted S. Warren First legal cannabis sales in Washington Washington's cannabis stores Brian Travino, a student at Western Washington University wears a Washington state flag, as he waits with other customers to purchase recreational marijuana at Top Shelf Cannabis in Bellingham, Wash., in the first half-hour of legal sales in the state. AP Photo/Ted S. Warren First legal cannabis sales in Washington Washington's cannabis stores Amber McGowan, left, and Krystal Klacsan, right, work at the recreational marijuana store Cannabis City in Seattle to apply a state-mandated frosted film to the front of a display case that will contain pot varieties when legal sales begin on Tuesday, July 8, 2014. The store will be the first and only store in Seattle to initially sell recreational marijuana on Tuesday. AP Photo/Ted S. Warren First legal cannabis sales in Washington Washington's cannabis stores A customer, who declined to give his name, sniffs a strain of recreational marijuana at Top Shelf Cannabis, Tuesday, July 8, 2014, in Bellingham, Wash., during the first half-hour of legal sales in the states. Customers cannot be given samples, but are allowed to use "sniff jars" to help make their purchasing decisions. AP Photo/Ted S. Warren First legal cannabis sales in Washington Washington's cannabis stores Julian Rodriguez, right, of Everson, Wash., holds his two-gram packet of recreational marijuana outside Top Shelf Cannabis, Tuesday, July 8, 2014, in Bellingham, Wash., on the first day of legal sales. At left is Tom Beckley, the owner of the store. AP Photo/Ted S. Warren First legal cannabis sales in Washington Washington's cannabis stores The price of two grams of a strain of marijuana named "Sweet Lafayette," is displayed at Top Shelf Cannabis, Tuesday, July 8, 2014, in Bellingham, Wash., on the first day of legal sales of recreational marijuana in the state AP Photo/Ted S. Warren

"At first I thought it was someone's hedgerow rubbish. I went down to get the bags so the sheep weren't eating black plastic.

”When I got there I realised it was a form of herbal cannabis plant. They were very strong in scent.“

The farm sits next to a road and footpath. Mrs Budd said had the fly-tippers gone 200 yards further they would have seen the farm shop, adding: “They probably didn't think anybody would find it.”

The remainder of the drug stash has since been removed by police and incinerated.

Det Con David Fair told the newspaper the dumping of the illegal plants had been “extremely irresponsible” and said police were “doing all we can” to find those responsible.