SNP MPs are angry with the party leadership over the continuing delay in allowing Michelle Thomson back into the parliamentary party, believing it to be a “denial of natural justice,” senior party sources have claimed.

The Edinburgh West MP, who is said to have a property portfolio worth £1.5 million, resigned the whip in September 2015 after it emerged that her former solicitor, Christopher Hales, had been struck off for professional misconduct for his part in 13 of her property deals.

Police Scotland have been making inquiries into this matter for more than a year but the force is not investigating the MP over any wrongdoing.

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At the time she resigned the whip, Ms Thomson made clear she would co-operate fully with the authorities and stressed that she had always acted within the law.

She added: “Once the investigation is concluded, I look forward to returning to play a full role in party activities. I will be making no further comment on this matter."

The 51-year-old politician was regarded as one of the SNP’s rising stars before she resigned the whip. She was its Westminster spokeswoman on business and during the independence referendum campaign had been managing director of the pro-independence group Business for Scotland.

In the run-up to the SNP’s autumn 2016 conference, reports suggested that Ms Thomson was about to resume the Nationalist whip after the Westminster group of MPs called for their former colleague to be readmitted.

However, a meeting of the party’s National Executive Committee decided that the matter would be "continued for further consideration".

One party figure within the Edinburgh West constituency claimed that if Ms Thomson were reinstated, the party would lose the seat at the next General Election, saying: “Politically, she is toast.”

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The local MP, who now sits as an Independent in the House of Commons, holds the seat with a 3,210 majority. She won it from the Liberal Democrats in 2015 on a 14.3 per cent swing.

However 15 months on from her resigning the whip, colleagues at Westminster are increasingly incensed by her continued exclusion from the party, it is claimed.

One colleague explained: “Moves are afoot to get her back in but people are really angry at the delay. We feel it’s a denial of natural justice.”

Another said: “Michelle should be back; there is no case to answer. I’m pretty sure everyone in the group feels the same.”

Asked if the leadership was dragging its heels, they replied: “No comment.”

A third source stressed how they would have no objection to Ms Thomson resuming the party whip but appreciated it was “politically sticky” and added: “I can see why she and others might be frustrated at the lack of progress.”

When it was suggested that the leadership had to make sure all official inquiries had been concluded thoroughly before it could consider welcoming Ms Thomson back into the fold, one party insider said: "If that's the view, it's a disgrace."

Asked about the suggestion that MPs are angry with the leadership about Ms Thomson’s continued absence from the party, an SNP spokesman replied: ''This is a matter for the NEC of the party.''

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In July, Ms Thomson emailed colleagues about her "distress" and strenuously denied her firm had targeted "vulnerable people" to snap up homes at knockdown prices.

Last week, the MP hit the headlines after revealing during a Commons debate that she had been raped at 14. She has since spoken to the police but has expressed no desire to “go after” her attacker.

The backbencher explained that her aim had been to reassure others they had support, not bring her rapist to justice after 37 years. Ms Thomson insisted: "I'm not a victim, I'm a survivor."