I can just recall the silver threepenny bit in the Christmas pudding, but I think they'd all been lost by my adolescence. I don't know about the buying power of the dodecagonal version, but I can remember being able to buy a poke of chips for 3d around 1960.

In 1960, 3d was the standard child fare on an Edinburgh bus, 6d for adults. I remember my grandmother once showed me a silver thruppence, but I don't remember what it looked like. But here's a site with more info.

I'm pretty sure I remember seeing a silver 1.25p piece when I was very young, but I don't think we still had them for the Christmas pudding. I expect INJ had eaten them all.

CdM, you just made milk come out of my nose. I wouldn't have minded so much, but some of the cornflakes I was eating as I read took the same route.

[SM] I'm re-assured that you were eating cornflakes at the time. I'd be worried if this was a phenomenon that could occur spontaneously.