The scholarly consensus today holds that most of the Sonnets were written in the 1590s, when Shakspere of Stratford was in his late 20s to late 30s, a relatively youthful age even in Elizabethan times.
Not only were they unconvincing on many specifics (they initially opposed the nationalisation of Northern Rock, a failed mortgage lender, for example), but Mr Cameron's thriving attempt to rebrand the party as sunny and youthful suddenly jarred with the bleaker times.