Hi Pitxu,
The terminology gets a bit confusing (sellers on ebay call them all sorts). Think that plate holder is probably the correct term for what you are looking for, and the inserts are most often called film sheaths (the adaptor to use sheet film in a glass plate holder). I guess you are looking for 665/7 holders? I'm always looking for 726/7 holders, which are a bit less common.
Whereabouts in Wales are you from? I'm from Rhondda.
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