Also see Class 303 section

In 1967 additional stock was required for the extension of electrified services on the South bank of the Clyde and 19 Class AM11 (Class 311) sets were ordered from Cravens. These were virtually identical to the Class 303 sets previously in use in the Glasgow area, recognition between the two batches was possible as vents were provided on the bodysides of Class 311 power cars.Slightly more modern decor interior including strip lighting was used, but externally the sets were finished in standard BR blue.
Although the Class 303s were refurbished from 1984, the Class 311s were not included.
After rail blue livery came the standard blue and grey colours. After withdrawal in 1989-90, two sets were retained in Scotland as Sandite delivery units, but these have now been withdrawn and disposed of.