Billion Dollar Brain was the third and final movie in the Harry Palmer spy series, starring Michael Caine.
What started out in The Ipcress File as a grittier, more realistic take on international espionage than the James Bond series had by the time of this third instalment morphed into something approaching Bond-level of supervillain craziness. The sense of un-reality was heightened by being directed by, rather curiously, British enfant terrible Ken Russell.
I don’t remember much specific about this, other than a climactic scene when an army convoy assembled by a mad renegade general is bombed on an ice-covered lake and everyone, general included, sinks below the ice.
This French grande poster has a nice 60s pop art feel to it and is for sale here.