Why are the Liberal Democrats doing so badly?

On the face of it the political climate is primed for the party to be attracting a raft of new members – and more importantly, of course, new votes. And yet their poll rating is in stasis and the party is struggling for any kind of cut through.

Neither prime minister Theresa May or Labour leader Jeremy Corbyn have won the hearts (or minds) of the majority of people. Consistently polling has shown that the most popular prime minister of the United Kingdom would be 'none of the above'.

So, Sir Vince Cable's Liberal democrats should be motoring.

The Tories are ripping themselves apart over Europe – what has changed in the past 40 years? – and Labour is engaged a torrid and increasingly brutal internal war.

The Lib Dems on the other hand are united behind their leader – although patience is beginning to wear thin – and policies.

And yet they go into the conference, which starts this weekend, in Brighton floundering. And no-one really knows why.

The centre of British politics is barren. The space Tony Blair's Labour occupied with such success for so long and where David Cameron so firmly planted his Conservative regime has been abandoned.

And yet there is nothing to suggest the electorate have shifted. More than half of voters now say that neither Labour nor the Tories represent their views.

The stage should be set for a Lib Dem revival. So what exactly is going on?

As it stands there is a tranche of people – a sizeable grouping – who don't think Labour or the Tories represent their views and yet are happy to carry on voting for them regardless without even casting an eye over the Lib Dem's policies.

Many people – including this columnist – expected the Lib Dems to be in a much healthier place after the 2017 general election. As the only truly anti-Brexit party they spoke for a very large contingent whereas the Tories and Labour appeared happy to accept the referendum result.

But they stalled. Some of that failure has to be placed at the feet of then leader Tim Farron who managed to kick off the campaign by getting himself embroiled in a debate around gay sex which in time would end his leadership.

Surely in the safe hands of Sir Vince – a well-known and liked political figure – the third party would become resurgent? Well, not yet at least.

So, on the eve of conference what exactly are the Lib Dems proposing?

Sir Vince wants this conference to be about more than just Brexit. That policy alone has not brought the party the success they desperately need so they must flesh out other areas as well.

The party is convinced they can prise Labour voters away from Mr Corbyn by adding policies to fight the stagnation of living standards into the mix. Sir Vince knows that a lot of Labour voters are uneasy with the party's stance on Brexit and longs for the centre to back the Lib Dems.

Proposals include:

• Replacing business rates with a land-value tax;

• Overhauling inheritance tax allowing everyone to give £250,000 over a lifetime tax-free before income tax rates apply;

• Introducing a flat-rate of pension tax relief.

The Lib Dems will claim these proposals alone could generate £15 billion a year.

All ideas many people would support or at least be sympathetic towards. But the Lib Dems need to face facts: it will be a long time before they can rebuild to the position they occupied after the 2010 election.

So is there another answer? Should the Lib Dems consider doing something radical?

Sir Vince has held meetings with centrist MPs concerned about the general direction of their respective parties. He has probably simply tried to convince them to cross the floor and join the Lib Dems but maybe something else is stirring.

Some kind of new formation is possible – but it would be difficult. The Lib Dems could offer the perfect platform for it to be a success though.

Perhaps if enough MPs were to join them – and a little rebrand – the Lib Dems could offer hope for those who feel ignored in the centre.

They would need a new leader – in the shape of Mr Blair or French president Emmanuel Macron – but the policies are broadly there already.

And the formation of a new (ish) party would generate huge media coverage. The opportunity is there – but will the Lib Dems take it?