Sentinel 'Spectacle' Windows Wanted
 

Wanted:
Four 15 inch diameter, circular, 'spectacle. windows for Sentinel 7109's restoration. See the picture below.
https://lh6.googleusercontent.com/-n...e+Cropped1.jpg
Ideally, I would like genuine Sentinel windows as used on many of their early locomotives but suitable alternatives will be considered.
The original windows were lost during transfers between previous owners and have never been found.
Thanks in anticipation.
Andy