These are very, very light. The one on the right is an Austrian one made of aluminium; the other two date from 1940s Netherlands and Germany, where heavy metals were in short supply, and are made of zinc. Over 200 million of the German ones were minted, so they're not worth anything.
How they wound up in gas meters in a small coastal town in East Yorkshire is a mystery, but sounds like the kind of thing that people doing creative writing courses might be asked to write a short story to explain.