Excavation works in my office

I will present a result of excavation works in my office,
namely a forgotten theorem of Plotkin: adding fixpoint
combinator to simply typed lambda-calculus does not
enlarge the class of definable functions. The contents
of the 1982 handwritten note was demonstrated at the
occasion of the 90th birthday of Dana Scott.

https://www.youtube.com/watch?v=n7moEQtv3qU