Hi,
I would put your bike at about 1911 or12. I once owned CY 491 which was a 1910 AC Sociable. The Swansea records are still in existance and you can contact the record office at West Glamorgan Archive Service, County Hall, Oystermouth Road, Swansea SA1 3SN Phone 01972 636589 or Fax 01972 637130. Another Swansea bike I had wes CY 4917 which was 1922. Hope this is helpful. Best wishes Tim R-R