With all due respect to Martin Richards, neither did his BCPL, given that bytecodes as idea go back to compilers being developed in 1950's after FORTRAN came to be, and was already part of CPL ideas anyway.
If fact there were all operating systems written with such ideas like Burroughs B5000 in 1961, nowadays still sold by Unisys, and thanks to this approach being easily retargeted to modern hardware.
Why this "who did it first thread?" in first place?
You had commented before I created a new account, so I will just add that I have never seen Wirth claim that he or his colleagues at ETH were the originators of the idea. Moreover, this idea was already used in Wirth’s “first” language, namely Euler, which he published in 1965 while at Stanford. An even earlier example may be Schorre’s META‑II from 1964 (UCLA).
Regarding the popular opinion here that Pascal was created for educational purposes (only) - implicitly meaning not for building real, large-scale software - Wirth considered these two characteristics equivalent, and in his view one was a necessary condition for the other.
From the summary/abstract of his original publication about Pascal (The Programming Language Pascal) written in 1970 and published in Acta Informatica in 1971:
In view of its intended usage both as a convenient basis to teach programming and as an efficient tool to write large programs, emphasis was placed on keeping the number of fundamental concepts reasonably small, on a simple and systematic language structure, and on efficient implementability.