LONDON (Reuters) - Rishi Sunak is forecast to become the first sitting British prime minister to lose their own parliamentary seat at an election, a Savanta opinion poll published by the Telegraph newspaper ahead of the July 4 national vote showed.

Savanta polled around 18,000 people between June 7-18.

(Reporting by Kylie MacLellan, Writing by Sachin Ravikumar; editing by William James)