A Vietnamese man who admitted his part in a huge cannabis factory will be jailed, despite having two indictments against him dropped because a police officer who was needed to give evidence had moved to Australia.

Truong Vu, 43, of no fixed abode, pleaded guilty at Kingston Crown Court on Monday to one count of cultivation of the class C drug when Three-hundred plants were found at a house in Montem Road, New Malden and he was charged with similar offences at two other cannabis factories. But the Crown Prosecution Service said it would drop two of the charges, partly because a PC Connelly mislabelled an exhibit. He was needed to attend court to clarify but he moved to Australia some time ago and there was no chance of his return. In light of the guilty plea for Montem Road, the CPS decided it was simpler to prosecute on just one count.

The factory is thought to have run from November 2005 to January 2007, although the CPS admitted not knowing how much Vu grew and whether he was simply a foot soldier in a much larger criminal drugs organisation.

The house, the court heard, was rented by a woman who is still wanted by police and is associated with a number of other cannabis factories found in suburbia.

Vu, who has been in the UK since May 2004, was arrested in connection with a cannabis factory in Malden Road in December and was charged for the Montem Road plants in January, after police found his fingerprints at the address.

Many of the jobs he has done have been organised through the Vietnamese community and were often only in exchange for a place to stay, the court heard.

His defence claimed he was only in Montem Road for three weeks, tending the plants for a friend, but the CPS said fingerprints found on two 600 watt bulbs in the house indicated he played a more pivotal role.

Vu, who wore casual clothing in the dock, spoke through an interpreter only to plead guilty. He will be sentenced on June 15.