Yeah I think the fact that it is a picture of a picture taken at an angle that distorts the image a bit. If you have a spin around at this viewpoint on google maps you can see the topology of the hills lines up nicely:
Many thanks guys, really helpful. I think the jury comes in with Loch Lomond. The shop owner who has this on their wall will be chuffed to finally put this debate to bed! 😀👍