Visited British Motor Museum at Gaydon, Warwickshire today. Say some interesting cars, including these three. From left to right - Jaguar XK150, XK140 and XK120.
Looking closely at the bonnet of the XK150 (nearest) you can see a 80mm wide raised section running from front to back, which was not there on the xK140 or XK120. It transpires that when the XK150 was built, the car was widened, and rather than design a new bonnet, the XK140 had a section inserted in the middle, You can see evidence of this on the dashboard, and the front seats.