POLICE in Tavistock are warning shops and businesses in the town to be on their guard, following a spate of opportunist thefts during the last couple of weeks. PC Steve Bradfield said the incidents had all occurred in the town centre. He said: ?An individual has walked into private areas of shops and businesses and either stolen or attempted to steal cash or goods, during office hours. ?Basically we need to ask people to be more aware, make their offices more secure and be observant of visitors into their premises.? PC Bradfield said people should make sure their valuables were kept in a secure place and that they should not be left in coat pockets which may be hanging outside offices.