Found in an old box in the club second hand stock. Not Lego, although it looks a bit like it, but plastic blocks from the Italian firm Montini.
Digging around the web, it seems that these might date from the 1950s or 60s. They may even pre-date Lego. Someone suggests that the boys from Denmark ripped off Montini because the Italians didn't register the design. If that's true, there is some irony that Lego have since lost a trademark dispute and the world is full of notLegos with are compatible but not the same.
The plastic these are made from is very soft and flexible. The designs aren't great, but then neither were early Lego models. Children had much better imaginations back then.
Montini produced quite a range of kits, these are the bottom end as there were pretty substantial sets too. Sadly, that's all I can deduce from Tinternet. Can anyone add to the story?