The No 11 is actually a very early plane dating back to Leonard Baileys days before he came to The Stanley Rule and Level Company. It was produced between 1867 and 1943.
The 11 was a Belt Makers Plane – not like the one you put around your waist. If you thing about the beginnings of the “Machine Age” factories used line-shaft and leather belting was the norm for transmission. So being able to trim a belt was a factory necessity.
Between 1909 and 1923, they ground off the No 11 in the body casting and replaced the toe late with a longer one. This was called the 11 1/2 and it was used as a flooring plane… probably not a very fun flooring plane.
These are low angle (25 degree bed) bevel up planes. If you pick one up at the right price it could double as a low angle mitre plane.