If this is STILL on his grave, that would be a disgrace. This is a temporary marker, placed prior to the final marker. And it is done in a generic typeface used on (plastic) engraving machines (think pantograph and stencil-like masters).

A modern equivalent would be Interstate by Font Bureau.

. . .
Bert Vanderveen BNO

Gravur Condensed from Lineto replicates the clumsy charm of engraving/stencil type:

http://lineto.com/The+Fonts/Font+Categories/Text+Fonts/Gravur+Condensed/

... or Gravostyle.

or Router or DIN 17.

Thank you!
And I am quite sure it is STILL the plate under the rosebush where Sellers' ashes are buried. In Golders Green Crematorium, London.

Now I came across Andy Warhol's grave... Any ideas?

http://www.flickr.com/photos/wm_archiv/2672219430/

@meister: I think some 'fonts' are simply letters cut for certain purposes and don't have digital equivalents, in the case of Andy Warhol's grave, that could be the case. A gravemaker's machine that sets type on film for sandblasting. But i couldn't tell you anything else. I simply don't know.

This is a great thread, though morbidly interesting.