I don't think this list has absolutely everything, but the range does look rather limited, until you take into account that the reference data sheets (covered here as "duplicate and back sheets") would have numbered several hundred since they started being produced in 1910.
It was 1921 when Norman & Hill Ltd. began local UK manufacture and distribution of the Lefax products. The Filofax name was coined about four years later by Grace Scurr, who had been taken on by them as a temporary secretary. It only came into prevalence much later on though. And Grace Scurr famously saved the company, but that's another story!