SNOW showers and gusty winds blasted the Northern Isles at the weekend, terrible conditions for election teams to be out chapping doors.

"It's not been too bad," insists Liam McArthur, the Scottish Liberal Democrat candidate in the seat of Orkney, who like his opponents is more used to foul-weather canvassing than most.

Even so, it's touch and go whether the stunt he has planned for tomorrow - a trip out to Scapa Flow on a small dive boat - will be possible.

Politics is different in the Northern Isles and it is not just down to the weather.

The party tribalism of much of Scotland has not taken root in the close knit communities. Independents dominate the local councils and the tradition of voting Liberal Democrat has remained strong at parliamentary elections.

Like everywhere, though, strongholds of any colour are under threat from SNP yellow.

Mr McArthur, who succeeded Jim Wallace as Orkney MSP in 2007 and held the seat at the last election in 2011, faces a tough battle to defeat SNP candidate Donna Heddle, a professor of Nordic Studies at the University of the Highlands and Islands, who finished third with a decent 25 per cent of the vote five years ago.

It is a similar story in Shetland, where the Lib Dems' Tavish Scott, an MSP since 1999, faces a strong challenge from Danus Skene.

Mr Skene, a septuagenarian, Eton-educated clan chief, has enjoyed an eclectic political career, having been a senior figure in Labour in the 1970s and a LibDem councillor in the 1980s.

He switched to the SNP a decade ago and, in last year's General Election, came close to unseating former Scottish Secretary Alastair Carmichael as MP for the combined Westminster seat of Orkney & Shetland.

Mr Carmichael clung on by 817 votes but quickly had to admit his role in the leak of a Scotland Office memo designed to damage Nicola Sturgeon.

He was taken to court by constituents who failed to oust him but left him badly damaged.

Mr McArthur says the bitter fight, which had the support of the SNP, "backfired," as many voters felt the MP had been unfairly hounded.

To the surprise of some, the SNP has not sought to capitalise on his lapse, at least in official campaign literature.

Ms Heddle says she is not raising issue as Mr Carmichael is not standing, but takes a different view of its significance. "It is coming up on the doorsteps, a lot of people are quietly furious," she says.

In the public hustings, local issues have taken centre-stage, with questions about the ferry fleet and fares.

Will the Scottish government extend the generous arrangements enjoyed in the SNP-voting Western Isles to Orkney and Shetland? There is no clear answer but the government has promised to improve broadband connections and an Islands Bill, that will devolve some powers from Edinburgh.

As well as fighting on their records, Mr McArthur is confident both he and his colleague Mr Scott will pick up plenty of tactical votes in two of the few constituencies in this election which are genuinely in play.

Ms Heddle also says her campaign is going well. Boosted by a visit from Ms Sturgeon, badges are selling out.

"Here it tends to be douce and genteel. This time it is entirely different," she says.

The one thing both sides agree on is the results in Orkney and Shetland will be close.

READ MORE: Five constituencies to keep an eye on in the Holyrood election

Candidates for Orkney:

Paul Dawson, Independent; Donna Heddle, SNP; Jamie Halcro Johnston, Scottish Conservative; Liam McArthur, Scottish Liberal Democrat; Gerry McGarvey, Scottish Labour.

2011 result:

Liam McArthur, LibDem - 2912 (35.7%)

James Stockan, Ind - 2052 (25.2%)

Donna Heddle, SNP - 2044 (25.1%)

Jamie Halcro Johnston, Con - 686 (8.4%)

William Sharkey, Lab - 458 (5.6%)

Majority - 860; turn out - 49.3%

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Candidates for Shetland:

Robina Barton, Scottish Labour; Tavish Scott, Scottish Liberal Democrats; Danus Moncrieff Skene, SNP; Cameron Smith, Scottish Conservatives.

2011 result:

Tavish Scott, LibDem - 4462 (47.5%)                                        

Billy Fox, Ind - 2845 (30.3%)

Jean Urquhart, SNP - 1134 (12.1%)                          

Jamie Kerr, Lab - 620 (6.6%)                       

Sandy Cross, Con - 330 (3.5%)    

Majority - 1617; turn out 53.4%