Hi, seeing these pieces suddenly I thought the same, 1950's Whitefriars- or Czech as choices. The "bullseye" type pattern suggests as much. The Skrdlovice bullseye pattern pieces in this timeframe are very difficult to attribute conclusively at the best of times. Your pieces are in a colour that makes me hesitant to suggest Skrdlovice, but apart from the shade of yellow, it would be possible. The silence from Whitefriars enthusiasts, suggests that it seems they don't think Whitefriars likely.... though the colour to me looks more that way, than 50's Skrdlovice... sorry not to be more helpful...
Robert (bOBA)