Just acquired a beautiful Brsdm. Gilded Urchin x Onc. Orinthorhynchum cross. I'm a beginner and haven't any idea of what to call this. It's flowers look like Urchin, but are brownish purple and gold.
As you have written it the Brassidium would be the seed parent and the Oncidium the pollen parent. I could not see a cross listed as you have written it in the RHS database.
However the reverse cross is listed, that is Oncidium ornithorhynchum x Brassidium Gilded Urchin. This was registered as Brassidium Golden Gamine in 2006.
And, just to keep the confusion to a minimum, for registration purposes it does not matter what the order of the parents are. The 'reverse' cross is also Brsdm. Golden Gamine.