I think it may have been a love token, but to whom? I was thinking Victoria to John Brown, but if so, she must have changed her mind because the gifts she'd given him were (I think) mosty returned when he died in the 1880s. I doubt he gave it to her as in would have been wildly above his means. Its subject matter suggests some intimacy, so I doubt it was an official gift (which would have been logged anyway). Maybe someone from the public sent it to Victoria anonymously so it was impossible to return? I have a feeling there's a story behind it.