I found this on Worthpoint.com but have not researched in the National Archives yet. The four digit code beginning with a 6 is an internal product code used by Duron.
Wall plaque by Duron – Reg 885796 / 6017
The site for everything to know about DURON, Paoli, Nieri and Bacci vintage african black chalkware / gypsum sculptures and figurines made in the 1950s and 1960s
1950s vintage chalkware statues 
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