Just when you think their moral waterline had been holed so frequently that they could not submerge any further they go and add another few tonnes of cargo to ensure the process of plumbing the depths continues unabated.

Cue the Tories’ latest election wheeze, which has to be one of the most cynical, deplorable and spectacularly ill-judged in recent times.

Thus we were presented in eye-watering technicolour with a picture of David Cameron choking a baby sheep to death for its milk bottle on the front page of every rag in the country.

At least that’s what it looked like to this column and you can’t tell it otherwise.

Quite what the Tories hoped to achieve with this jaw-droppingly crass photo op is beyond this column’s ken — but apparently someone thought it was a good idea.

Probably someone called Tristram.

It was probably supposed to be a twee Easter/spring new beginning motif, but instead conjured up images of lambs to the slaughter.

But then this whole fiasco of an election campaign has come to resemble one of those really annoying magic eye pictures stoned students used to stare at for hours, where if you squint you see a dolphin and then realise you just wasted several hours of your life for nothing.

A remarkably similar effect is induced by listening to any of these morally bankrupt, Janus-faced shysters for more than a couple of minutes.

Nick Clegg has spent the Lenten period bumbling around doing his usual impression of the Easter bunny — selling tantalising myths of bountiful benefits to youngsters in the full knowledge it’s their parents who will have to pick up the tab.

As the minute hand of the doomsday clock continues its inexorable progress towards the mutually assured destruction that is May 7 the country is beginning to resemble one of those dystopian sci-fi films, like the Matrix.

Things seem normal enough on the surface and the population sleepwalks along none the wiser as their robotic overlords continue to pull the strings behind the scenes. But then you start to notice strange glitches in the programme.

The masks begin to slip and their true characters emerge.

Worse still, strange gangs of ravenous and crazed creatures are roving the streets ready to pounce ferociously on the unwitting to serve their own nefarious purposes.

Oh, they call themselves “canvassers” but we know better.

It’s not 26 days to the election, its 28 Days Later.

And speaking of fantastical creations with profoundly creepy overtones, curiously (or should that be curiouser?) and somewhat fittingly this election year also marks the 150th anniversary of the publication of Lewis Carroll’s seminal (and I use the term advisedly) opus Alice in Wonderland.

In fact Carroll’s tale could act as an allegory for this whole election thus far. Peopled almost exclusively by demented, self-absorbed individuals who never give anyone a straight answer and conjured up by someone you wouldn’t let anywhere near your daughter.

Tory policy can be anthropomorphically represented by the White Rabbit — never on time and always vague about the details.

Ed Miliband and Ed Balls are of course Tweedledum and Tweedledee.

George Osborne is the obviously the Cheshire Cat. You’re never quite sure where he is but have a constant feeling he’s somewhere smirking behind your back.

Ken Clarke is the caterpillar. Given to gnomic utterances behind plumes of smoke and no-one is entirely certain what he has to do with anything anyway.

Vince Cable and Danny Alexander are the flamingos. Solid-headed creatures utilised by the Queen of Hearts (Cameron) for knocking awkward shots into the long grass.

And of course Ukip is basically the entire Mad Hatter’s tea party with Nigel Farage as the maniacal milliner at the helm.

Incidentally, as a minor point of historical interest, the notion of the mad hatter came from the fact that mercury was used extensively in the creation of chapeaux during the period the book was written. The constant exposure to the poisonous fumes had deleterious effects on the mental faculties, hence the phrase “mad as a hatter.”

Almost exactly the same effect occurs if one reads the Ukip manifesto.

Someone who obviously hadn’t read the document in question, but probably should have, was Ukip’s prospective candidate for Stoke on Trent South Tariq Mahmood.

Mahmood had the dubious distinction of being selected to represent his party on a televised TV debate on black and minority ethnic issues on Thursday night. To be honest, they didn’t really have that many options open to them.

To say that Mahmood participated in the debate would be somewhat wide of the mark. His entire contribution was to look terrified and stammer “Nigel says” at periodic intervals. This had the unfortunate effect of conjuring up “Eine Volk, Eine Reich, Eine Fuhrer” as declaimed by a primary school snitch.

Not that the others were any better.

The Tory merely reverted to type and brayed at anyone who criticised him while banging on about how working class he was with an accent you could cut glass with.

The Labour candidate tied herself in knots trying to avoid the blatant fact that the majority of the rubbish she was regurgitating could have come from the Tory manifesto.

And the Lib Dem did nothing but try and attack the Tory over the joint policies the coalition has made and appeared to be desperately distancing himself from Nick Clegg.

He’s not the only one. Apparently great swathes of Lib Dem candidates are putting out campaign literature pointedly excluding any reference to their being Lib Dems.

That’s just the kind of bold conviction politics that’ll win over the electorate.

It’s like the electoral equivalent of the witness protection programme.

To paraphrase the much lampooned rallying cry from David Steel: “Lib Dems, go back to your constituencies and prepare for ignominy.”