I have lost the Tag for this Oncidium, and finding it difficult to find what it really is. I thought that it might have been Onc. Sweet Sugar, but I am now doubtful.
The Spikes do not branch, the flowers are pretty small 2.5cm and the little "skirt' is 1.5cm.
Any help or guesses would be much appreciated.
It doesn't look like Sweet Sugar to me. I wouldn't be surprised if it was a Oncidium sphacelatum but it could just as likely be a hybrid. You'll probably never know for sure.