But .... look

IS electric infrastructure invest by the UK government a Good Idea?  Of course.  And I doubt I have to 'splain why.

Will it kick-start a round of economic vitality.  Almost certainly no.

We know this from the affects on the economy from the history of the Rural Electrification Program carried out in FDR's administration.  Yes it brought electric power to the rural areas.  It did not promote a wave of use because the farmers couldn't afford to purchase products, e.g., milking machines, that could take advantage of it.  

She believed in nothing; only her skepticism kept her from being an atheist. -- Jean-Paul Sartre