Aircraft-engine ident.

Gentlemen, 

One more identification. A friend of mine would be delighted to know wich aircraft-engine he was sitting on, 50 years ago. The picture was taken on the Belgian seaside, end of the 60’s.

Engine: seems to be Merlin (according to rockers covers…). But the engine could be upside-down…

Prop: blades seems in feather position (multi-engine ??)

Backplate / prop hub: it seems the backplate is not in line (with prop hub). Prop hub seems English-American…

No exhaust pipe to see…

Thanks for comments. And take care of you and family.