Thames Valley Police has seen the number of metal thefts reduce by nearly half in the last financial year.
From April 2012 to March 2013 there were 2,052 thefts of metal, compared with 3,924 the previous year.
All 35 scrap metal dealers in the force area were visited and asked to join a voluntary scheme where transactions would require supporting identification documents.
A large-scale operation called Operation Symphony tartgeted dealers who were believed to be involved in illegal activities.
Last May, 400 officers conducted multiple warrants on business and private premises across the area. As a result, 28 people have been charged with about 200 offences relating to metal theft.