Tuxedo shirt - ya?
Tried on today and it fit okay for a RTW shirt in a 15.
Link : http://www.us.thomaspink.com/Marcella-Evening-Super-Slim-Fit-Double-Cuff-Shirt/Evening-Shirts/thomas-pink/fcp-product/99920821#filters=!$FIT!super+slim+fit+shirts
UK 9 Rain I actually never tried on. SA only had 8.5UK which was very very snug in a captoe oxford. 9.5UK I had heel slippage. 9UK in Rain 2 eyelet chukka seemed okay, but not sure how that translates into other shoes.