Ages ago I remember seeing a sort-of manual cement mixer; can't recall
details as I wasn't particulary interested at the time, but I think it
was a drum with mixing vanes that you rolled about on the ground or
something?

Just that these days I find myself mixing smallish quantities fairly
often; can't really justify buying a proper mixer and haven't got the
storage room anyway (I do one-day hires from HSS when needed).
Advancing age means it's increasingly hard on the old back, and I'm
looking for a better long-term solution.

Does anyone know if these things are any good, and if they are still
around? (my guess is "no" and therefore, "no" but just wondered!)

David