it's a singer 327 made between 1960 and 1965. above the stitch regulator lever there is a tiny number on the plate that's the model number. Ismac has a manual available. it's a lovely machine. mine is a 328k and it has the ability to use different cams. oh and she uses class 66 bobbins
manual:
http://ismacs.net/singer_sewing_mach...ine-manual.pdf
from your photo: http://i.imgur.com/jvm7jv5.png it's a 327k so it's from Scotland