The No. 1 was in the NID period Ithaca catalogs from 1926 through 1934. From the large 1928 Ithaca Gun Co. catalog, sorry my scanner won't do their whole 14" pages --
No. 1, 1928 Catalog.jpg
The No. 1 was gone from the 1935 and onward Ithaca Gun Co. catalogs along with the cocking indicators. However, they did continue to make a few. My No. 1 28-gauge without cocking indicators shipped in late 1935 --
459536 01 NID No. 1 28-gauge.jpg
The bold floral engraving pattern was introduced during 1915 on the Flues No. 1 1/2 --
Ithaca Flues No. 1 and one half, July 1915.jpg
During 1919 Ithaca combined their No. 1 and No. 1 1/2 and the New No. 1 had the bold floral engraving.
No. 1 Dec. 1919 color catalogue.jpg