As a journalist at Westminster, she is a keen observer of political gossip, intrigue and in-fighting.

But now Serena Cowdy is at the centre of her very own bust-up after having affairs with two married MPs from the same party, the Daily Mail can reveal.

Stewart Hosie, 53, and Angus MacNeil, 45, have each left their wife following a relationship with the 36-year-old writer.

The Scottish National Party MPs are said to have clashed over their rivalry for Miss Cowdy's affections.

Mr Hosie, deputy leader of the Scottish National Party, announced on Sunday that he was separating from wife Shona Robison, a senior politician in the Scottish Parliament.

He did not mention his relationship with Oxford-educated Miss Cowdy but it is understood that Miss Robison learnt of her husband's affair ten days ago, when he confessed.

Mr MacNeil announced his separation from his long-suffering wife Jane last year, not long after the end of his affair with Miss Cowdy, a former actress who is now a freelance political journalist.

Mrs MacNeil had stayed with her husband after a previous embarrassment, when he was caught with two teenage girls in a hotel room in 2007 while she, then pregnant, was in hospital.

Miss Cowdy is said to have told friends that she saw SNP MPs as romantic revolutionaries, describing them as 'the Mujahideen of British politicians'.

A source said: 'This love triangle is a disgrace for Scottish politics – and gives weight to the rumours that some of the sudden mass of SNP MPs in London have been going on a big jolly.

'These two have behaved with all the decorum of a coach party in a Carry On film arriving at a pub.

'It's laughable that Serena boasts of her affairs with these MPs and says they're like a sexy Mujahideen. I doubt their wives think they are.'

When asked about her affairs with the politicians last night, Miss Cowdy said: 'No comment.'

The MPs and their now-estranged wives also declined to speak.

An SNP source confirmed the story but disputed a claim that love rivalry led to a row between Mr MacNeil and Mr Hosie.

Father of three Mr MacNeil, who previously worked as a BBC Scotland reporter and a teacher, represents the Western Isles. He rose to prominence in the Commons in 2006 by lodging a complaint with police over 'cash for peerages' allegations made against Labour.

Angus MacNeil, 45, announced his separation from his long-suffering wife Jane (pictured together) last year, not long after the end of his affair with Miss Cowdy, a former actress who is now a freelance political journalist

Stewart Hosie, 53, deputy leader of the Scottish National Party, announced on Sunday that he was separating from wife Shona Robison (pictured together), a senior politician in the Scottish Parliament, following his affair

Earlier this year he faced questions over his own probity when he had to repay hundreds of pounds in expenses after claiming more than £250 a night for hotel rooms, when the usual limit is £150.

An acquaintance of Miss Cowdy's circle, who revealed the love triangle, told the Mail: 'Serena is from London and went to Oxford, but since starting work in Parliament has this thing about the SNP being like the Mujahideen.

'She was having an affair with Angus MacNeil during the Scottish independence referendum campaign – and boasted that when he was on TV talking about it, she's texted him and he'd looked at his phone. He used to take her to the Park Plaza hotel in Waterloo for the night. Now she's with Stewart Hosie and has been for some time and it's very serious.

'She's suggested for a while he's going to split from his wife and they're going to have a proper relationship in public. Now he really has separated we'll have to see. I heard things had been difficult between Stewart and Angus because they'd both had the same girlfriend – and that there have been cross words between them.

'Surely MPs are paid to represent their constituents – not gallivant round London having affairs with the same woman. It is even more wrong if that interferes with their working relationship.'

Another source told the Daily Mail there had been a 'bust up' between the two MPs in Parliament. However, an SNP source insisted there was no overlap between Miss Cowdy's relationships with the MPs and no tension or rows between the politicians. 'The first relationship ended before the second began. Stewart and Angus have been getting on together fine,' the source said.

Miss Cowdy, from London, described herself as a 'mostly out of work actress' after gaining a 2:1 in modern history from St Hilda's College, Oxford.

She appeared on TV nature programmes for some years.

She now describes herself as a political journalist with Parliament's The House magazine while illustrating her website with a series of glamorous pictures. She has also written blogs about having office affairs and how to end a relationship in a series of articles about dating. She covered issues including 'The dos and don'ts of dumping etiquette', and 'An office affair: Needs must'.

She has admitted to engineering 'chance' meetings with men she wants relationships with. She even joked about being a 'stalker'.

On the subject of the end of relationships with previous boyfriends, she wrote: 'It's a bit depressing to think you wasted all that time with a complete loser'.

The Mail first approached Miss Cowdy and the MPs about the affairs last week – but they said nothing until a bland announcement about Mr Hosie's separation from Miss Robison was issued to a Dundee-based paper on Sunday.

Miss Cowdy is said to have had an affair with Angus MacNeil (right) during the Scottish independence referendum campaign before moving on to a relationship with Stewart Hosie (left) which is said to be 'serious'

An SNP spokesman said of Mr Hosie and Miss Robison: 'Stewart and Shona have separated. They have a young daughter, and she will continue to be their priority.

'Both parties have asked that their privacy is respected during this difficult time. No further comment will be given.'

During their 20-year marriage, Mr Hosie and Miss Robison became one of the most powerful couples in Scottish politics. At the weekend, it was reported that there had been rumours of strain in the marriage for some time.

Embarrassingly for Mr Hosie, party leader Nicola Sturgeon, Scotland's First Minister, is a close personal friend of Miss Robison, 49, who is health secretary in the Scottish Parliament.