British Prime Minister Boris Johnson led lawmakers from all parties in the service for lawmaker Sir David Amess, who was murdered on Friday.
Amess was stabbed at a church on Friday in a town just east of London.
Police arrested the 25-year-old son of an ex-media advisor to a Somali Prime Minister at the scene.
Services for Amess were held at Saint Margaret's Church at Westminster.
There were two hours of tributes to Amess from his colleagues in Parliament before the service.