In the antiques trade,
in American English, we refer to these as pull-out breadboard ends. I think the Brits call them Stowleaf Extensions. Here is an example that cites all four of those terms: (scroll down to "Stowleaf"),
http://www.dutchcrafters.com/furniture/glossary/
something similar...
I actually saw something very similar today at one of the local shops I stalk. It was made by brdr furbo and marked made in denmark. The example I saw had seen better days but functioned in a very similar manner to your table. it also shared many of the same style queues.
Hope that helps.
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