Injured jockey Davy Russell has failed to get a medical clearance to ride in Britain despite being allowed to ride in Ireland and will miss the Grand National meeting.
Russell partnered Lord Windermere to win the RSA Chase on the Wednesday of Cheltenham, but suffered a heavy fall later in the afternoon.
Although he returned to action the following day, Russell had to be taken to hospital for treatment after two rides when it was revealed he had sustained a punctured lung.
After receiving a medical clearance in Ireland and opting to postpone further treatment until the end of the season, he was back in action on the Thursday after Cheltenham.
However, Russell has been told by the British Horse Racing Authority he cannot ride in Britain where the three-day National meeting starts on Thursday.
"He went to London on Thursday to see the BHA's specialists and they just wouldn't pass him," Russell's agent Andrew Kelly said.
"He's ridden since the injury, is riding tomorrow and feels 100 per cent.
"It seems a strange decision but Dr (Michael) Turner just wouldn't pass him."
Jamie Stier, director of raceday operations and regulation for the BHA said safety was paramount.
"The BHA places rider safety as a top priority, and because of this Davy Russell's condition has precluded him from race riding in Britain under the terms of the BHA Standards of Fitness to Ride.
"The Standards are very clear on this specific condition as it may recur at any time and could form a potential risk to himself or other jockeys.
"Ultimately the decision was taken by the Licensing Committee to uphold their recommendations.
"We are aware that the Turf Club has given Davy approval to ride, however, as with many regulatory areas, there are variations between authorities and it is not surprising that different jurisdictions might have different views on this case."