Waterford Crystal: the sponsor Sir Anthony O'Reilly, the chairman of Independent News and Media, is Cian O'Connor's godfather. He has been the main sponsor of the rider's career since O'Connor was a teenager.
A spokesman for Sir Anthony said the businessman was flying and was not contactable yesterday evening.
A spokesman for Waterford Crystal, which is currently a sponsor of O'Connor's horse, said that the company was awaiting the outcome of tests on the second sample before making any comment on the case.
When the rider won the Olympic gold medal in August, Sir Anthony wrote warmly of his association with his godson in an article in the Sunday Independent.
According to the businessman, 10 years ago, when O'Connor was 14, he came to see him at his home in Castlemartin, Co Kildare, with "a singular commitment to a singular idea" of becoming a world class showjumper.
Sir Anthony became godfather to Cian O'Connor through his close friendship with O'Connor's grandfather, Karl Mullen, the Irish international rugby player of the 1940s and 1950s.
When he was 16 years old, Cian O'Connor prepared a business plan, which he presented to Sir Anthony in order to obtain the financial support to become a professional showjumper, including the purchase and sponsorship of his horses, including Waterford Crystal.
On the weekend after O'Connor's Olympic victory, Sir Anthony wrote:
"My wife Chryss and I and Independent Newspapers and Media and Waterford Crystal bought last night's star, Waterford Crystal, on Cian's recommendation and so a marriage that started with a determined glint in a little boy's eye ten years ago ended with the ultimate achievement of an Olympic gold medal in the clear air of Athens on a Friday night."