Movie where diamonds are send through ordinary mail.

The movie I am trying to find is probably set in Britain (London?), in color, probably from the 70s. Possibly of espionage theme. I remember a scene where there's a house with stairs that lead up to several offices... someone sends one of these offices, that looks vacant, unoccupied, diamonds through ordinary mail... Someone tries to rob these diamonds and/or there is a killing in those stairs...


Thank you!

The only movie that I found that has a similar theme is Diamonds Are Forever from 1971. It is a James Bond movie starring Sean Connery as the British spy. It is about a diamond smuggling investigation that leads Bond to Las Vegas, where he uncovers an evil plot by his old enemy Blofeld. In one scene, Bond visits an office building where diamonds are being sent through mail to an empty office.


But perhaps it my mistake and I don't remember exactly.

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Diamonds Are Forever is the first thing I ran across as well. But then I thought, "Nah, it couldn't be that simple, could it?"

The Anderson Tapes?

I didn't see the start of TCM's broadcast tonight, but, from memory, I am fairly certain that this is The Mackintosh Man (1973) https://en.wikipedia.org/wiki/The_Mackintosh_Man