British police have arrested a man on suspicion of murdering Ann Widdecombe, a British right-wing politician who was found dead on Thursday with serious injuries.

Ms. Widdecombe, 78, was a former lawmaker and government minister who found new fame after she left the British Parliament, appearing on popular TV shows, including the British equivalent of “Dancing With The Stars.”

In a statement on Friday afternoon, the police said they were called to an address in Haytor, in Devon, southwest England, by the ambulance service on Thursday, where Ms. Widdecombe’s body was found having “sustained serious injuries.”

At a news conference several hours later, the police said they had arrested a 26-year-old man in Newton Abbot, in Devon, and said that the incident was not being treated as a case of terrorism.

Matt Longman, assistant chief constable at Devon and Cornwall, said he had “no information” to suggest it was “a politically-motivated crime.”

That will be a relief to politicians in a country which has seen two fatal attacks on lawmakers in the last decade.

Asked whether the arrested man was known to Ms. Widdecombe, Mr. Longman said it was too early in the investigation for him to comment and that detectives were keeping an open mind.

The news sent shock waves through British politics, and the home secretary, Shabana Mahmood, said she was “deeply saddened” to hear of Ms. Widdecombe’s death. “The circumstances of her death are extremely distressing and my thoughts are with Ann’s family and loved ones,” she wrote on social media.

Prime Minister Keir Starmer described the development as “really shocking” and described Ms. Widdecombe as a “distinguished politician.”

Ms. Widdecombe served in the British Parliament for more than 20 years, until her retirement in 2010, and was a government minister in the 1990s under the Conservative prime minister John Major.

After Britain voted by a narrow margin to quit the European Union in a 2016 referendum, Ms. Widdecombe joined the Brexit Party, led by Nigel Farage, and represented it as a member of the European Parliament from 2019 to 2020. When the party changed its name to Reform U.K., she became a frequent spokeswoman for the party.

In 2010, she took part in “Strictly Come Dancing,” the dancing contest, and appeared on “Celebrity Big Brother,” a reality show, in 2018.

While she may have lacked finesse on the dance floor Ms. Widdecombe won over many Britons through her self-deprecating approach and willingness to entertain viewers with comedic performances.

As a lawmaker in the 1990s, Ms. Widdecombe had a reputation as a committed conservative and a forthright politician who spoke her mind. She converted to Roman Catholicism in the early 1990s and took a strong interest in moral issues, consistently opposing abortion, gay rights and assisted dying.

During that period she fell out with her boss, the then home secretary, Michael Howard, over his sacking of the prison service director Derek Lewis in 1995. She accused Mr. Howard of having “something of the night” in his personality — a phrase that stuck and set back his political advance.

The police on Friday said that a cordon was in place at the property where Ms. Widdecombe’s body was found, while specialist officers continued forensic examinations. They also appealed for any witnesses who had seen unusual activity to come forward.

“We are particularly keen to hear from anyone who may have seen anything suspicious in the vicinity of Haytor Vale, Haytor, or anyone with CCTV, doorbell or dashcam footage which could assist with our investigation,” the police statement said, while appealing to the public not to speculate on social media about what might have happened.