An Albanian PE teacher who was brought to this country "in the back of a lorry" was found looking after more than 500 cannabis plants with an estimated street value of £275,000. 

Illegal immigrant Kristian Zefi quickly tried to escape from an upstairs window onto a flat roof at the two-storey, 12-room industrial premises and ran onto the roof of the next building. The premises had been barricaded from the inside to prevent nosy passers-by from getting in and disturbing the "sophisticated" cannabis growing operation inside, Hull Crown Court heard. 

Zefi, 28, of no fixed address, admitted producing cannabis on June 16. Stephen Welch, prosecuting, said that police executed a drugs warrant at the premises in Popple Street, Hull, a large two-storey industrial building with about 12 rooms.

"As police attempted to gain entry, the defendant exited from an upstairs window onto a flat roof in an attempt to escape," said Mr Welch. "He appeared agitated and made his way to the roof of an adjoining building. 

"He made at least one call from his mobile phone and eventually surrendered to police approximately 55 minutes later. On entry to the premises, the police found a sophisticated cannabis grow with in excess of 500 plants."

The likely yield was said to be 27.5kg, with a potential street value of £275,000. "The exits were barricaded from the inside but there were power tools within the premises," said Mr Welch. 

"The doors had been secured not to keep the defendant inside the premises but to protect the premises from trespassers. The occupants would use the roof to both exit and enter the premises." 

Zefi later told police that he had been trafficked to this country and claimed that he had been beaten up, although a bruise on his arm did not match his description of the supposed attack. "He claimed to being monitored to make sure that he did not escape," said Mr Welch. 

"The defendant performed a limited role upon direction and he had no influence on those above him in the chain." Rachel Scott, mitigating, said that Zefi had a university degree in physical education and, before coming to this country in May, he worked as a PE teacher in Albania.