Thanks so much for getting me where I needed to go Oliver.

I realised that the article-reveal component had something similar so I cribbed something from that and inserted where you advised:

this.$el.velocity("scroll", {
      delay: 400,
      duration: 1000,
      offset: this.$el.height() - $(".navigation").outerHeight()
});

Works great in FF at least!

Regards, Chris