Wow thanks! That is a really interesting article!Yes, she went on to double for Joanna Lumley in The New Avengers as well, so she had a long history of the show. Happy to be of help! There's a good shot of Cyd from her time doubling for Diana (complete with flipped up Emma hair) here if you're interested. (Go to the second page for the picture).
It has made me realise that I think I may have another photo of her as well:
It is from the same batch taken on set in 1968 and
I'm thinking this resembles her in that second page photo..
![Image](http://i1286.photobucket.com/albums/a602/A_diabolical_mastermind/av2_zps5b441d2c.jpg)