Winning large show hack at the Horse of the Year Show (HOYS) Opium Casa Leona has been stripped of its height certificate by the Joint Measurement Board.

Howard Robinson, who runs the JMB, told H&H there were concerns about the identity and age of the mare owned by Southampton-based showing producer Adam Winbourne.

“We are led to believe that the same horse has two passports under two names,” said Mr Robinson.

“But I am assured by the owner that this matter will be speedily resolved and the certificate can be reissued.”

A spokesman for HOYS said the class result would stand because “the concern was a passport irregularity rather than a height issue”.

Mr Winbourne told H&H that the case has now been resolved.

Two horses connected to Mr Winbourne were stripped of JMB certificates before HOYS.