TO BORROW a phrase from Oscar Wilde, one must have a heart of stone to read about the resignation of Norman Baker without laughing.

The Lib Dem Home Office minister has deserted his post because his boss Home Secretary Theresa May lacks the collegiate touch and refuses to embrace policies based on reasoned evidence.

In short, Mr Baker has discovered after just 12 short months in post that Ms May is, horrors, a Tory! Such powers of insight should guarantee him a glittering career on the Commons back benches.

An enlightened populace will hail future revelations that the pontiff is of the Holy Roman Church and ursine creatures defecate in wooded areas.

But his resignation begs the question of what the Lib Dems imagined they were doing when they entered into a sub-Faustian pact with the Tories after the 2010 general election, exchanging the remnants of their integrity for a semblance of power and status.

They had fought the election on a platform of rejecting the “austerity-max” policies of Cameron and Osborne, in favour of “austerity-lite.” They opposed any further increase in student tuition fees and any majority sell-off of Royal Mail. Indeed, the Lib Dems had pitched their appeal to traditional Labour supporters as the “real party of opposition” to the Tories.

They now claim that entering into coalition with Theresa May’s self-confessed nasty party has curbed Tory excesses while delivering at least some progressive policies.

A brief perusal of the 2010 Lib Dem manifesto quickly dispels such self-serving, dishonest pleading. There was nothing in it to signify subsequent support for such excessively reactionary measures as the bedroom tax, the gagging Act, sweeping NHS privatisation and the wholesale closure of Remploy factories, let alone for the brutal slash-and-burn acceleration of austerity.

Instead of helping to drive such policies through the Commons as cat’s paws of the most right-wing British government since the 1930s, the Lib Dems could have blocked them in opposition. A minority Tory government might have been compelled to moderate some of its more anti-social and anti-democratic proposals.

As for Mr Baker’s attempt to introduce reasoned evidence into government thinking about illegal drugs, his prospects of success were always nil. This is a regime, remember, which claims that public servants cause recessions, the unemployed cause unemployment, housing benefits create a housing shortage, foreigners precipitate a financial crisis in the NHS and prisons solve crime.

Not that the Labour shadow cabinet produces much “rational evidence-based policy” in many of these areas either.

But at least Mr Baker leaves the Home Office a wiser if sadder man. He likens his time there to “walking through mud.”

That mud should stick to the Lib Dems for a generation, hopefully consigning them to the oblivion they so richly deserve after next May’s general election.