The announcement of an agreed unionist candidate for Fermanagh/South Tyrone puts an end to the Conservative Party pledge of standing in all 18 Northern Ireland constituencies.

Rodney Connor has agreed to take the Tory whip if elected. But he is standing as an Independent.

And he is also reserving the right to vote as he pleases on Northern Ireland matters.

That's a far cry from being a fully-fledged Tory MP.

The unionist unity deal in Fermanagh South Tyrone highlights a major stress line — some would say contradiction — in the thinking behind the UUP's pact with the Conservatives.

In traditional unionist terms, an agreed candidate makes sense.

It gives the cause a great chance to win a seat from Sinn Fein.

And unionism has traditionally been a catch-all political force, bringing together right, left and all shades in between.

But where does a pan-unionist front fit with the Conservative pledge of offering all Northern Ireland voters a new start in politics, a chance to vote on “national” issues for a party that won't take sides here?

Critics will now accuse David Cameron of very much taking sides — of lining up behind a candidate alongside the DUP and, presumably, the TUV as well.

The move will see the SDLP facing calls to stand aside.

And it may well lose votes to Sinn Fein as nationalist voters go down the traditional Northern Ireland route of trying to keep the other side out.