Eventually constant intertwining linear maps between complete locally convex spaces

Starting from Sinclair's 1976 work {\it Automatic Continuity of Linear Operators}, Cambridge University Press, (1976), on automatic continuity of linear operators on Banach spaces, we prove that sequences of intertwining continuous linear maps are eventually constant with respect to the separating space of a fixed linear map. Our proof uses a gliding hump argument. We also consider aspects of continuity of linear functions between locally convex spaces and prove that such that a linear function $T$ from the locally convex space $X$ to the locally convex space $Y$ is continuous whenever the separating space $G(T)$ is the zero vector in $Y$ and for which $X$ and $Y$ satisfy conditions for a closed graph theorem.
Comment: Several minor errors corrected. Accepted for publication, November, 2019, in Italian Journal of Pure and Applied Mathematics, to appear in 2021