In contrast, more than 300 seats across England and Wales are considered "competition free zones" by the Electoral Reform Society (ERS), which is campaigning for an end to the first-past-the-post (FPTP) voting system used at Westminster elections.
Aberdeen North, Dundee East, Glenrothes, and the Inverness, Nairn, Badenoch and Strathspey constituencies are all highly likely to be defended by the SNP at the 2019 general election, the ERS said.
In England alone, 300 seats are classed as safe – 56 per cent of the total – covering 22,007,281 potential voters. The ERS claimed the ‘scourge of safe seats’ is made worse by Westminster’s winner-takes-all voting system.
Marginals are usually defined as seats where a swing of up to 10 per cent will lead to a change, with the average swing between the Conservatives and Labour in the post-war period around three per cent.
By this standard, around a quarter of seats that will be contested on Thursday across the UK can be classed as marginal. But in Scotland, that figure rises to three-quarters – or 46 out of 59 seats.
There are ten constituencies north of the border where MPs are defending majorities of fewer than 270 votes.
ERS chief executive Darren Hughes said: “While we don’t know who’ll form the next government yet, we do know this: in hundreds of seats across the country, the result feels like a foregone conclusion.
“This election is being fought in the handful of swing seats that hold the keys to Number 10. Meanwhile, millions of people in Britain’s one-party seats feel like there’s almost no election at all.
“Some of these constituencies are so secure that we’re confidently predicting the outcome in 316 seats – half of constituencies in Britain. That means 23 million potential voters are in seats highly unlikely to change hands."