Whatever spin is being employed, the Conservative/UUP tie-up has taken a real battering in recent days.

The alliance had the potential to come apart due to being pulled in different directions.

Unionism has always been first and foremost a catch-all movement — what political scientists would call an all-class alliance.

The historic links between the UUP and the Conservative Party were for the most part more apparent than real. That was evident when the Stormont administration in the 1940s fully imported the Labour Government's welfare state to Northern Ireland.

And in 1985 Margaret Thatcher spared little thought for Jim Molyneaux's feelings when she signed the Anglo Irish Agreement.

There were grounds for scepticism when David Cameron came along and started talking about creating a new force here with veteran unionist Sir Reg Empey.

Promises were made about not taking sides and building a new non-sectarian future.

The plan did attract some new people into politics, and gave the UUP a much-needed morale boost.

But now the Ulster Unionists may be pulled along a more traditional route — of banding together to keep “them'uns” out.

There is a cold, old-fashioned logic to the calls for unionist pacts, and it is clearly a tempting prospect for some in the UUP.

Unionist unity would be likely to play well on the doorsteps, and could wrest Westminster seats from nationalists and the First Minister's desk from Martin McGuinness.

But even showing an interest in such a direction calls the rhetoric of the Tory link-up into doubt.

How can you not take sides if you are thinking of moving towards a pan-unionist front with the Orange Order cheering you on?

Cameron should also be aware of the potential risks to him from the speculation of recent days. He has made much of moving his party to a socially liberal position..

Whatever old-guard views may still exist in his rank-and-file, the Conservative leader will not be hitting out at single mothers or pandering to homophobia. Those kinds of views would be toxic to his cause.

So would he be able to live with a three-in-the-bed scenario with the DUP? And what does all the unionist unity speculation do for the Westminster principle of bipartisanship on Northern Ireland?