The sister of a student who died from an undiagnosed heart condition is to take up a place on Trafalgar Square's Fourth Plinth in his memory.

Sian Thomas, 26, from Llantrisant, is one of 2,400 people selected to perform on a topic of their choice on the plinth as part of the One and Other project, created by artist Anthony Gormley. 

Her hour in the spotlight of Trafalgar Square will come on September 28, when she will raise awareness of sudden cardiac death in young people. 

Sian's brother Gareth, an international politics graduate, died in February 2007, aged just 21.  He was found dead in bed at the house in Alfred Street, Roath, Cardiff, he shared with friends. 

Mum Anne, a former cardiologist, speaking after the football fan's inquest, said: "In most cases these defects can be spotted with an ECG scan." 

Since his death, Sian has dedicated much of her time to raising funds for charity, Cardiac Risk in the Young (CRY) as well as highlighting awareness of sudden cardiac death in young people. 

Sian said: "I feel privileged to have been offered a place later this month and to have been given an opportunity to pay tribute to my brother in such a public way. 

"There was really no doubt in my mind as to what I would do during my hour and I really do hope passers-by will take the time to stop and think about my message. 

"Screenings are available though CRY and many of these tragic deaths could be prevented if young people or their parents were aware that a simple test could identify a ticking time bomb before it's too late." 

Alison Cox, chief executive and founder of CRY, said: "We were very proud when Sian told us of her plans to stand on the Fourth Plinth as part of her ongoing awareness activity for Cardiac Risk in the Young. 

"She will be taking part in an historic and memorable event and helping us to reinforce our important message to a worldwide audience. 

"We must do everything we can to continue to raise awareness of the importance of cardiac testing in young people, especially those involved in physical activity." 

In the Trafalgar Square project, "plinthers" stand on the plinth for an hour and can do whatever they want in that time, so long as it's legal.  The 24-hour-a-day project has run from July 6 and will last 100 days until October 14. 

Among those previously chosen to stand on the plinth from South Wales have been people campaigning to save popular Cardiff pub The Vulcan, and a member of Llandaff Cathedral's organ appeal.