One of the bonnier pictorials in this collection – it’s a hand coloured photograph or a watercolour painting, and yes there’s a pronounced green tint on front and the printing on the back is in the same green.
So somebody went to the Isle of Wight, perhaps on holiday. Or one of the Crosbys knew someone who lived there, or visited. And the postcard itself was printed in Germany.
Maybe the little pencil squiggle was the beginning of an address to be written, and the writer thought better of it and wrote a letter instead? What do you think?