A WESTMINSTER by-election is due in the coming months after a long-serving Labour MP quit her role to take on a job in the NHS.

Rosie Cooper, who has represented the West Lancashire constituency since 2005, revealed in a statement that she will be leaving the constituency to become chair of Mersey Care NHS Foundation Trust.

The West Lancashire by-election will mark a first major test for new Prime Minister Liz Truss. Under Boris Johnson’s leadership, the Tories floundered in a number of by-elections in the last year.

The seat looks like a safe one for Labour, thanks to Cooper’s majority of 8336 and polling currently in the party’s favour.

In her statement, Cooper said it had been “an incredible honour” to serve the area for 17 years.

“I appreciate this will come as a surprise to many people having recently secured reselection to stand as West Lancashire’s Labour Party candidate for the next General Election,” she said before clarifying that the NHS job offer came after that process.

“The National Health Service is one of my passions,” she added. “Prior to entering Parliament I had dedicated many years of service to the NHS and have been able to serve on the Health and Social Care Select Committee during my time as MP.”

She offered the “very best for the future” to the constituency residents and thanked them for the “faith” they placed in her since her election.

Labour leader Sir Keir Starmer said Cooper would be missed by her constituents.

“Rosie’s commitment to the Labour Party and to West Lancashire as their Member of Parliament since 2005 has been inspiring,” he said.

“As well as being a dedicated champion for her constituents in Parliament, Rosie has paved the way for the deaf community and future generations by securing the British Sign Language Act.

“Her constituents hold Rosie in the highest regard, a testimony of 17 years of hard work and commitment to them. I know she’ll be missed.

“It has been a privilege to work with Rosie and I wish her all the best in her new role and for the future.”

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According to Westminster rumours, ambitious Labour mayor for Greater Manchester Andy Burnham has previously had his eye on Cooper’s constituency as a way to return to the UK Parliament.

The National: Could Andy Burnham be planning a return to Westminster?Could Andy Burnham be planning a return to Westminster? (Image: PA)

It's also thought that the fracking issue could play a major role in any by-election campaign, with the UK Government looking to end the ban on the practice.

"Fracking could well be an issue in the campaign, with the Preston New Road drilling site just north of this constituency. Cooper has strongly opposed shale gas extraction," climate journalist Rich Collett-White explained.

Cooper has been a controversial figure among Labour MPs at times, having voted against the legalisation of gay marriage in 2013 and against extending abortion rights to Northern Ireland just three years ago.

The terrorist plot

In 2019, a far-right terrorist was jailed for at least 20 years after plotting to kill Cooper.

Jack Renshaw purchased a 19-inch knife with the aim of murdering the MP and taking revenge on a police officer investigating him for child sex offences.

The 23-year-old admitted to making preparations to kill Cooper at a trial at the Old Bailey.

The National: Jack Renshaw. File photo.Jack Renshaw. File photo. (Image: Jack Renshaw. File photo.)

Justice McGowan told Renshaw at the time: “This is a case in which only a sentence of life imprisonment can meet the appalling seriousness of your offending."

Cooper said she believed justice had been served in the court. “Not for me personally, but for every MP and public servant, and for our democratic way of life which affords us the privilege of free speech, without fear of violent retribution,” she said in a statement.