Mention of SEGOM in a comment on the previous post got me searching around the Internet again, and I came up with some new things. These are other people's pictures - if I've borrowed your picture then it's a great picture, and I'm not making anything out of it, so thanks very much!
It seems that SEGOM did indeed produce a 54mm acetate series, and one of the forums I was looking at suggested that they produced these (cheaper) figures to compete with MDM, who were very successful with their Serie de l'Epoque Napoleonienne. There seems to be some confusion between SEGOM and MDM anyway, but the more I look at the MDM examples the more I start to think that maybe my remembered wooden mounting blocks were actually black plastic, and that the labels may in fact have been white! The labels look very familiar...
The first picture are actual SEGOM, apparently, while the rest are all MDM (though some were claimed to be SEGOM). The strange round black base in the final picture is the end cap of a clear plastic box in which the figures were sold.
So I think my figures may well have been MDM, of which I had never heard until this evening. It seems that MDM also made a more expensive series of metal figures - not sure of the scale. If anyone has some actual knowledge on this subject (and I certainly do not!), then please do chip in! I also remember the figures as being rather more attractive, and better finished, but no matter.
Life is like that, I find.