As they say in French, j'ai ravisé.
I put the painting aside - I normally leave it for longer than I did, but the reflection niggled at me. I wasn't satisfied. So I rechecked the photo portfolio I had taken of the set-up (I always photograph my still life set-ups, from different angles, different exposures etc to cover all bases). I decided that a photo that displayed more of the reflection was what I was after, so I brushed off the excess pastel (out of doors) that was covering the area I wanted to alter. I then turned the photo and the painting upside down, drew in the outline of the new relected dalla, and used a mixture of Rembrandt burnt umbers 403.3 and 403.5 series, and Sennelier Olive Grey 449/450 to paint the reflection. Highlights were added in Caran d'Ache pencil and diffused, then a spot of Sennelier Naples Yellow 103 dabbed into the centre. Background repairs were done with the Sennelier Lamp Black, and the painting put behind glass so I can't touch it again without the bother of unsealing and unframing it.