At the front end of the Canberra, there is a blanked out hole. On both sides of the hull.
In real life it's a bow thruster - an auxiliary drive at the front of a ship to allow the captain to swing the nose in sideways. Airfix put a blind hole in as a guide but then didn't follow through with a representation of the propeller that should be visible.
Undeterred, I drilled through the holes with a 4mm bit and scratchbuilt a suitable hole filler. The photo isn't great but you get the idea. The prop is made from a circle of plastic sheet with blades cut in it (I've assumed a 4 blade prop) supported on a length of plastic rod with some more to represent the central bulge that I assume holds the pivot and drive bits.
The design is a combination of ideas gleaned from a web search and what I reasonably thought I could build. It might be that there should be a grille of some sort over the hole but I reckon this would need to be so fine you wouldn't see it. Well, that's my excuse.