Kabel has a pre-digital history, but I couln't find a closer sample.
If it wasn't for the Futura-like M I'd go for a heavy weight of Avenir.
Maybe really a mix if the sample is really mid-60s.

Andreas

I’d say hand drawn, based on Kabel and Futura.
Avenir is around 1988

I've managed to identify the other two fonts on the button (Alternate Gothic and Mandate), so I believe that this one is most likely a font, too. And I'm sure I've seen that "G" before..

Here's the whole button with three others designs from the same era: http://cgi.ebay.com/BEATLES-Set-of-Four-3-5-Pinbacks-USA-1965-on-curl_W0...
might be replicas, but the design is authentic. I've seen an original at a museum.

I guess it could be Tempo Heavy: http://typophile.com/node/3673

edit: alright, found a specimen. it's spot on. Case closed.