Anyone able to suggest a match, or at least a passable substitute? 

Futura, but the M is different. Geometric 415 is close. Neutraface (from House Industries) would work. Avenir is OK too but some characters are different. Can't easily find an exact match but any of the above should do the trick. Neutraface gives you the funky 33.
Thanks for all that, Patricia and Yves. Jasper, Berry and Johnson have a showing of Granby, from Stephenson Blake, that has a similar 3, but other things don't quite match. I'm wondering if the 3s were from a different font.
Anyway, I'm thinking that maybe Relay would be another font that could pass.
Again, thanks.
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