Barker's fellow energy minister Michael Fallon was today promoted to the UK cabinet as defence secretary, and replaced by Matt Hancock as minister for business, enterprise and energy.

Hancock was formerly skills and enterprise minister.

Amber Rudd also joins DECC as parliamentary under secretary of state, in her first ministerial post.

Rudd replaces Barker, who had been central to the team helping to shape energy policy from the start of the Coalition government that took power in the UK in 2010.

Barker