The glass he was replacing was obscure glass - designed to let in light without revealing what is inside the room. The variety was known as "Large Flemish", and his question was intended to elicit whether I wanted the pattern one way up, or the other! Look at the central shape in the glass in the photograph - that's "elephant's bum" - from the resemblance to that creature's posterior. Now imagine the shape inverted - that's "tulip"! Simple, graphic, memorable. And splendidly silly!
All this was brought to mind when I took a photograph of a book I saw behind an open door glazed with "Large Flemish" glass. The image on the book was pleasingly distorted, and the colours mixed together in a manner that reminded me of Gaugin. I took several shots, and the one above is the best of the bunch. Photoshop? Who needs it? Here's the poor man's substitute!