This is confirmed to be the Canon Breech Lock mount introduced in 1959.
It was used before the new FD mount was introduced in 1971.
The FD mount is still a breech lock mechanism but sophisticated.
Both breech lock and FD bayonet lenses can be mounted on Canon bodies such as Canon F1-N, A1, AE1, T90 and so on.
The lens you showed is not an original Canon lens. But made for use in Canon manual focusing cameras.
We know just looking at it, even from the rear view, even if you did not show the front view.
The original Canon lenses got better machined parts and more elegant design. The original Canon lens use a well machined metal cam instead of the round rod (to act as automatic aperture lever) That is what you pay for when you use original lenses. (not even considering the serious lens glass quality difference)
wow thanks for the informative input guys ... really appreciate it. I was given this by my dad, ask me to sell it how much do you think it can fetch now? Think of putting it in buy and sell but donno how much to put.