IT is “really hard to imagine” the UK Government refusing to honour its state pension commitments to Scots in the event of a Yes vote, one of the country’s leading experts on the issue has said.

Writing in The National, former Tory pensions minister Ros Altmann warns that if the two governments could not reach an agreement post-independence then pension responsibility “would need to be challenged in court”.

Altmann says this would be extremely complex, drawing attention to the fact that it is “pretty much impossible to identify who paid contributions in Scotland, who paid contributions in the rest of the UK, what they paid, what their employer paid, and how each would be allocated”.

She further says that public sector pensions are another “minefield” which would require intense negotiations to navigate.

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“Ultimately, of course,” she writes, “it is really hard to imagine that the British Government could refuse to honour National Insurance state pension accruals in some way”.

After a distinguished career as an academic economist, Altmann was awarded a CBE in 2014 for services to pensioners and pension provision.

One year later, she was made pensions minister in David Cameron’s (below) government, having been elevated to the House of Lords to take on the role.

It was later revealed that Altmann had been a member of the Labour party when Cameron made her a Tory peer. She was expelled from the party as a result.

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While she has said she “absolutely hope[s the] UK stays together”, Altmann has recently used social media to criticise Unionists attempting to make the pensions debate seem clear cut.

Some of the confusion around pensions in an independent Scotland has centred on the idea of a “pot”. The term does not hold true for the current UK system, as current pensions are paid from current taxes; there is no savings fund being accumulated.

However, Altmann explained on Twitter: “Whether or not there is a fund, there is an accumulated benefit entitlement.”

People in the UK who have paid their National Insurance contributions for 10 years are entitled to a state pension. This rises incrementally until a person has fully paid those NI contributions for 35 years, at which point they become entitled to a full new state pension.

This can be seen under the current system, where people who live outwith the UK are still paid a state pension, so long as they have paid sufficient NI contributions.

The question is, in the event of a Yes vote, would the UK Government still have its legal obligation to pay people in Scotland who have at least 10 years of NI contributions a state pension.

The question is unanswerable at the current time. As Altmann said, any resolution would “have to be subject to mind-bogglingly complex negotiation and maybe painful compromises”.

The pensions expert said the current UK scheme relied “on assumptions which may or may not hold”.

“The system is a bit of a ponzi scheme,” she explained, “thinking more about the short term and just hoping all will be alright in the long term”.

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However, Kevin Hague, the founder of the pro-Union group These Islands, challenged Altmann’s view.

Hague said Altmann’s interpretation was “illogical and irrational” and called the idea that the UK would have an obligation to pay pensions to citizens of an independent Scotland the “ex-pat fallacy”.

He went on: “The UK Gov would have the power, justification and political imperative to not fund a seceded tax base’s pension.”

In a withering response, the peer wrote: “I'm afraid you’re not quite representing my points accurately. It's pensions and their rules that aren't always rational/logical.

“We could wish things to be otherwise, but legally this is all up for negotiation. However much we don't like something to be so, it may still be.”