Graham Gibbons, the leading jockey on the all-weather circuit so far this winter, has agreed to stand himself down "with immediate, indefinite effect" pending an inquiry into an incident at Kempton Park on Wednesday evening when he is alleged to have swapped a urine sample with a sample provided by a fellow jockey, Callum Shepherd.

Gibbons, who has a long record of offences and suspensions related to alcohol, and Shepherd, an apprentice rider, were among 10 jockeys randomly selected to provide a sample by a British Horseracing Authority drug-testing team at Wednesday's meeting. The local stewards subsequently inquired into "a report from the clerk of the scales that Graham Gibbons had substituted the urine sample he was required to produce with that of another rider, Callum Shepherd", and sent a report to the BHA's head office in London for further consideration.

A statement on the incident issued by the Professional Jockeys’ Association (PJA) on Thursday afternoon suggests that Shepherd initially agreed to exchange samples with Gibbons, but then assisted the racecourse officials in holding an inquiry into the “sampling irregularity”.

"Callum made a serious error of judgment," Paul Struthers, the PJA's chief executive, said, "but to his credit very quickly took steps to correct that error, which ultimately led to the subsequent stewards' inquiry into the matter, to which he gave candid evidence.

Legal representation

“The PJA can also confirm that Graham Gibbons has stood himself down with immediate, indefinite effect. The PJA is in touch with both jockeys and will provide all the necessary support. They have been assigned legal representation and will co-operate fully with the investigation.”

Gibbons has been a leading rider on the northern circuit in particular for more than a decade, and was on course to record his best season in the saddle with 93 winners so far in 2016, just five short of his total in 2013. He was leading the all-weather jockeys’ championship this winter. His big-race winners include Ajaya, in the Group Two Gimcrack Stakes at York in 2015, and Always Hopeful in the Group Two Richmond Stakes at Glorious Goodwood in 2005.

However, he was the first jockey ever to record a positive breath test for alcohol which exceeded the legal drink-drive limit when he failed a breathalyser before a meeting at Hamilton Park in 2007. He was subsequently banned for 35 days as a result.

Gibbons was also banned from driving for four years in 2011 after being found asleep in his car outside his house, having been reported to the police for appearing drunk after leaving after leaving a pub and then driving away. In April 2013, meanwhile, he was arrested at Wolverhampton racecourse by officers from West Midlands police having failed to attend Scarborough magistrates court three days earlier to answer a charge of being drunk and disorderly.

Jockey’s licence

Had Gibbons not decided to stand himself down, it seems likely that the BHA would have suspended his jockey’s licence pending a hearing into the case. A decision on whether he would be allowed to continue riding had been expected before Friday’s all-weather meeting at Newcastle, where Gibbons had booked rides in seven of the eight races on the card.

"The BHA cannot comment further regarding the incident at present as it is now an ongoing investigation," Robin Mounsey, the BHA's media manager, said on Thursday.

“However, this is clearly an issue that we are taking very seriously and we will be taking the necessary steps to progress this matter.”

The BHA has significantly increased the number of jockeys selected for breath and urine tests for alcohol in 2016, with the total expected to rise to 2,000 breath tests and 600 urine samples this year from about 1,000 and 300 respectively in 2015.

When a BHA testing team attends a meeting, it requires a breath test from every jockey due to ride on the card, while 10 riders are also randomly selected and asked to provide urine samples. Guardian Service