I sent Timdiggerm a PM, asking if it was a weaker yellow, like straw or cream, or a brighter, bolder yellow. This is what he said:
"Well, they were yellow. I'd say it was a fairly strong yellow, yes. Black border, of course. But no, I can't confirm this with photos, though I wish I could."
I have followed up with this, but I thought this was extremely interesting.