He was then caught attempting to swap urine samples with Callum Shepherd, who was not charged.
The Irishman had voluntarily not ridden since Dec. 9 and received a two-year ban by the disciplinary panel of the BHA due to the attempted urine switch and a six-month ban for the failed drugs test. The bans will run concurrently until June 8, 2019.
"Graham Gibbons, found in breach of Rule (D)65, received 6 months suspension from 9 Dec 2016 to 8 June 2017 inclusive," the BHA said on their official Twitter account.
"Gibbons also found in breach of Rule (A)30 and receives a two-year suspension from 9 June 2017 until 8 June 2019 inclusive."
The 35-year-old was on course to record 100 winners in a calendar year for the first time before the failed drugs test. He was previously banned from riding for 35 days after failing a breath test for alcohol in 2007.
(Reporting by Aditi Prakash in Bengaluru)