It's the simmer dim in Shetland now, what they call the perpetual daylight of the northernmost part of the UK. At the harbour of the islands' largest town, Lerwick, the union flag is flying, taut and horizontal in the wind. But on the fishing boats and on its notable buildings, the flags are all sky blue and white.

"The Shetland flag is an interesting symbol," said the editor of the Shetland Times, Paul Riddell. "The blue of the Scottish saltire flag with the Scandinavian-style cross – it accurately reflects the identity here. But we're Scots in attitude when it comes to our money and our politics."

At its most southern point, where Shetland's wildflower-covered hills slip into the North Sea waves, it is some 200 miles to Aberdeen and 200 miles to Norway.

Out Stack, at the other end of the islands, is the most northerly point of the United Kingdom, although that could change if Scottish independence became a reality. At least that was the idea until Tavish Scott, the MSP for Shetland, and his fellow Liberal Democrat, Liam McArthur, MSP for neighbouring Orkney, suggested that the northern isles could stay British, even if the rest of Scotland followed first minister Alex Salmond to independence.

As the referendum debate got under way last week with the unveiling of ex- chancellor Alistair Darling's coalition against an independent Scotland, Shetland, which only 500 years ago was Norwegian, will soon have to pick which flag is dearest to them.

"We are as distant in our heads from Edinburgh as London," Tavish Scott told the Observer, "and neither quite gets Shetland. Our connections are east towards Scandinavia, from historic times, and those connections can be seen in our place names, our timberclad houses. We were insulating our houses long before any green policy from the Scottish government!"

"There is a strong feeling here," he said. "It's that there is an opportunity in this referendum for Shetland to get what it really wants, which is more control of its own affairs.

"The point is that Shetland doesn't want the centralisation of the SNP. Devolution did allow Scotland to go its own way and now it should let Shetland go its own way. We will be working on producing a blueprint of what Shetland wants out of this."

The idea that these wind-scalloped islands could secede after a "yes" vote is seen widely as "mischief making" by the Lib Dem politicians. But the importance of the northern isles is not so much on land as in their water.

They are surrounded by oil. And gas and fish, all of which have helped create a thriving economy with zero unemployment and facilities and services that other communities of a similar size would rarely warrant from public funds. "It's a bit like a little Cuba," said Riddell, "a semi-socialist, semi-autonomous paradise!"

In a canny move when the oil companies began moving into its seas, building the Sullom Voe oil terminal in the 1970s, the Shetland Islands Council cut a deal that saw it keep control of the deep-water harbours the oil tankers needed, and take a percentage cut of every barrel of oil landed. The money went into a charitable trust for the island.

"The money is not what it was, but now the funds look to be replenished with a new gas pipeline that a French company are building and there are plans for a major wind farm that is stirring up controversy," said Riddell. He adds that there isn't a strong grassroots independence movement in Shetland as there was here in the 1970s and 80s.

"Like most island races, there's an established trait in our DNA that we're automatically suspicious of anyone or any change that comes by. That suspicion is still there, which is probably a good thing because it has led to our survival.

"Of course, Tavish Scott should be pushing for the best possible deal for Shetland, but he doesn't believe that Scotland, never mind Shetland, will vote yes, so it's mischief."

It is fair to say that the union has historically not always served Shetland well; the Acts of Union of 1706 and 1707 brought crown restrictions from London that destroyed the fishing trade and sent the islands into recession. Later islanders' seafaring skills made them targets for the British navy's press gangs.

Jean Urquhart is the SNP's list MSP in Shetland. She rejects the idea that Shetland would lose any autonomy in an independent Scotland and points to commitments from Salmond to increase powers for both the western and the northern isles. "The thing is that Shetlanders, like a lot of Scottish people, haven't really engaged in the debate yet, they're still waiting to hear how independence will look and feel," Urquhart says.

"The worst thing that could happen is for Shetland to drift into the referendum without having thought about how it would work for them. The point of independence within Europe is very clear. It's in the interests of the UK government to give away a few things to gain a few things in Europe. They have given away fishing. They have given away farming. We are a crofting and farming people. Shetland and Orkney would not be Britain's gain but Scotland's heartfelt loss."

In the stunning new Lerwick museum, the history books mention the old adage of the islanders: "All the Shetland ever got from Scotland was dear meal and greedy ministers."

But two years before they have to choose between London and Edinburgh in 2014, the islanders may well be like the rest of Scotland, still waiting to be won over by either camp.

In a bar overlooking the harbour, the tennis is on. "Aye, Andy Murray, he's British until he starts losing and then he'll be Scottish again," says the barman.

"Much like Shetlanders, they'll want us British until we're in trouble and then they'll be crying [calling] us Scots," said an old fisherman, tipping his pint at the screen with a grin. "Ocht, in the end maybe we'll away to join Norway."

• This article was amended on 30 June. The original confused the British Isles with the United Kingdom in a reference to Out Stack. This has been corrected