The passengers on board a horse-drawn carriage ride in the Swan Valley last month got more excitement than the brochure advertised when the flashing lights of a police motorcycle pulled them over.

Swan Valley Wagon Trails operator Ross Gundry was at the reins when he was pulled over on West Swan Road and fined $250 for being on his mobile phone while operating the wagon.

Ross Gundry was fined $250 and gained demerit points for using his mobile phone while at the reins of a horse-drawn carriage.

Mr Gundry said when the police officer told him why he was being pulled over, he questioned him, as he believed the law to cover motor vehicles, not horse drawn vehicles.

"He told me that the law changed last year changing to cover all vehicles, not just motor vehicles. I didn't know it'd changed," he said.