The experiment has proved a great success. The llama - called Lawrence - is gentle and has bonded well with the flock. But, best of all, since Lawrence arrived at the farm there have been no losses of lambs due to predators.
The farmers, Jamie Freeman and his father, Chris, bought the llama for pounds 500 from the Cotswold Llama Farm in Gloucestershire, after seeing a letter in Farmers' Weekly.
'He is also very economical,' Mr Freeman said. 'He eats grass, corn mash and hay, and costs less to keep than a ewe, weight-for-weight. Llamas have a very good conversion rate.'
Paul Rose, the owner of the llama farm, started the venture eight years ago after travelling in Peru.' There were llamas everywhere I went. I just became fascinated with them,' he said.
He now owns 100 llamas and sells between 15 and 20 a year. They are bought for a variety of reasons. Llama wool, for example, is very fine and is ideal for designer knitwear; the animals are useful for trekking since they can carry up to 200lb; and Mr Rose has even sold them as companions for horses.
But his real breakthrough came last year when the Iowa State University published a report recommending the use of llamas as sheep guardians. In the US, more than 5 per cent of sheep and 9 per cent of lambs are lost every year to predators such as coyotes, bears and foxes - causing losses in excess of dollars 83m ( pounds 56m) a year.
In the past farmers have dealt with the problem by using traps and poison, but these methods have serious ecological implications. One llama, however, can guard up to 2,100 sheep. They live for 12 years on average, although the oldest reported was 18 years old, and require no training, even though most have little or no experience with sheep. Participating farmers have reported a drop in losses from predators from an average of 21 per cent to an average of 7 per cent.
The main problem reported was of llamas becoming over-protective of their charges and refusing to let the farmer near. Some farmers also found their llamas trying to mate with the ewes.
Iowa State also issued a warning. Predators are notoriously quick at adapting to new challenges. However, the university said donkeys, kangaroos and ostriches also have excellent guardian potential.