Joan Branson, the wife of British billionaire Richard Branson, has died at age 80.

Branson announced her death Tuesday on Instagram and LinkedIn. No other details were disclosed.

"Heartbroken to share that Joan, my wife and partner for 50 years, has passed away," he said. "She was the most wonderful mum and grandmum our kids and grandkids could have ever wished for. She was my best friend, my rock, my guiding light, my world."

Richard Branson is the founder of Virgin Atlantic airline, space tourism company Virgin Galactic and satellite launcher Virgin Orbit.

In a 2020 blog post, he said he met Joan in 1976 at The Manor, a recording studio in Oxfordshire, England.

"Joan was a down-to-earth Scottish lady and I quickly realised she wouldn't be impressed by my usual antics," Branson wrote.

He said she worked at an antique shop that sold old signs and advertisements.

"I hovered uncertainly outside the shop, then built up the courage to walk in. ... Over the next few weeks, my visits to Joan amassed me an impressive collection of old hand painted tin signs, which advertised anything from Hovis bread to Woodbine cigarettes," Branson wrote.

The couple had three children, Holly, Sam and Sarah Clare. Sarah Clare died shortly after birth in 1979.