Only in Northern politics could one of the most predictable unionist constituencies transform itself into one of the most volatile, writes Dan Keenan, Northern News Editor, in Lisburn
For this, one has to thank Jeffrey Donaldson, once the holder of the prized largest vote in the Ulster Unionist Party. These days he is the standard-bearer for the DUP and doing much the same job at the polls for Ian Paisley's party.
Yet for all that, Lagan Valley could provide the surprises in the 48 hours after polling closes on March 7th.
Overwhelmingly unionist, this constituency also has a single nationalist quota and a dogged Alliance presence. There isn't room for a rising DUP vote, a UUP revival, a Sinn Féin gain or for the Alliance candidate to retain the personal vote of his predecessor. Something will have to give.
The DUP is housed in red-brick splendour in Lisburn city centre, with Jeffrey Donaldson's immaculate office at its core. His new party must ensure that his monopoly on first preferences doesn't cost the party the fourth seat it covets.
Paul Givan (25) is one of the bright young things of the DUP who is not satisfied with winning a council seat last year. He wants Stormont.
Affable and clear-headed, he'll tell you why it's the DUP and not the Ulster Unionists that is attracting a new generation of politicos born during the hunger strikes.
"I looked at Peter Robinson, Gregory Campbell, Nigel Dodds and Sammy Wilson. Compare them to the likes of Ken Maginnis, John Taylor - and I said 'Nah'." For him and his pragmatic brand of politics there's no crisis of conscience in sharing power with Sinn Féin. He doesn't like it - but he'll do it. He is anxious to get on with things, though there's a slight worry. There is a canvass this evening - but no party literature. It's a problem, but it's a laugh too. He's enjoying it. David Trimble lives in this constituency too. His door will be knocked. It'll be fun.
No such problems a short distance away in Twinbrook - Máiréad Farrell House to be precise - where Sinn Féin's Paul Butler is organising his next door-to-door swoop.
His campaign leaflet is gloriously simple - "Sinn Féin is the largest nationalist party in Lagan Valley," it proclaims - a fact illustrated with a stark graph. "Paul Butler is the only nationalist who can win the seat." It's as complicated as that.
The former prison buddy of Bobby Sands now has no war to fight. The task at hand is an electoral battle and his natural modesty and common sense mean he will not say it is over and won.
But the untold truth is that he could be sent to Stormont, possibly at the expense of the SDLP, who must fight this seat with a newcomer candidate in Marietta Farrell.
The other parties say they have no idea where the votes of Alliance pillar Séamus Close will go. He's retiring after more than 30 years of flying the party's colours.
Trevor Lunn, currently Lisburn's mayor, is a good candidate, the thinking runs, but that is no guarantee that all of Close's voters will stay. His party insists otherwise.
"It's an Alliance vote, not a Close vote," is the firm advice. "The two of them worked very closely as part of a team. Alliance is the only alternative to tribalism, the only ones delivering a shared future and standing against a carve-up."
Like the DUP, the Ulster Unionists' Basil McCrea is eyeing the Séamus Close vote, hoping enough of his supporters will spark a revival for his party after the reversal of the Donaldson defection.
He calculates his party has "about 1.6 quotas".
"The evidence is that if you get to 1.7, then you will probably get the extra seat." He hopes his better-established image, his campaigning stance on rates and at least some disenchantment with "the DUP U-turn" will add that vital 0.1 to the Ulster Unionist total. There will be some cheer if they pull it off.