The exact date of the Meltonian block products is now fixed. The product packaging was distinctly of the 1920’s and Germany was a key market so this did indicate a ‘between the wars’ period. But an advert found in a 1928 issue of the Wellington Evening Post confirms that Meltonian block products (as well as a variety of others) were on sale in the 1920’s.
More information:
Meltonian web page