The actress is known for her roles in Eastenders, The Bill, Heartbeat, The Professionals and Taggart, but made her name as Sam Hagen in Scottish soap Take the High Road. She stayed with the soap for almost a decade before leaving in the late 1990s.
Her husband David is said to be distraught at her death, with a friend of the actor telling a UK website that ‘he has lost the love of his life’.
Police were called to Fulham Broadway station, close to Briony’s home, at 8.35am on Wednesday with officers from the Met and British Transport Police arriving at the scene.
Fellow actor Colin McCredie, who played DC Stuart Fraser in Taggart, took to Twitter to pay his respects.
He wrote: ‘Devastating news. Such a brilliant lady, great company and a fine actress’.
He added: ‘I was very fond of Briony. I cannot believe it. She was so full of life and brilliant company. Poor David. She’ll be much missed’.
Take The High Road colleagues Andy Cameron and Gary Hollywood also expressed their grief via the social networking platform.
Agent Katie Threlfall described Briony as a ‘well-loved’ and a ‘vibrant’ actress, describing her death as ‘unbelievably shocking’.
Briony appeared alongside her husband and long-time friend Joanna Lumley in a production of Sir Walter Scott’s poem Lay of the Last Minstrel last month.
Her death comes in the same week as another former Eastenders star, Paul Bhattacharjee. His body was found at the foot of cliffs in Seaford, East Sussex.