An engine is described having a camshaft 10 formed of an inner shaft 12 and an outer tube 14 both of which rotate with respective groups of cams 18 and 16. A drive train driving both the inner shaft 12 and the outer tube from the engine crankshaft includes a phaser 30 for enabling the phase of at least one of the groups of cams 16 and 18 to be varied dynamically relative to the phase of the crankshaft. The phaser is secured to the front end of the outer tube 14 and the inner shaft 12 of the camshaft 10 is connected to the front side 36 of the phaser 30 by way of a driving member 46 that encloses the component 40 securing the phaser to the outer tube 14 of the camshaft 10.