Natal Maritime 1909 Cover posted on Sunday March 7th 1909 at Durban under the Sunday Late Fee serv

Cover posted on Sunday March 7th 1909 at Durban under the Sunday Late Fee service for overseas mail.
Sunday Late Fee mail was accepted at Durban and Pietermaritzburg to reach Cape Town for the Union Castle mail steamer which departed on Wednesdays for Southampton.
This late fee service is seldom seen, yet this unique supplementary charge was acknowledged in the Supplement of the Post Office Act of 1901 which listed the supplementary charge for postal articles: 27.For the acceptance at Pietermaritzburg and Durban on Sundays of ordinary letters for overseas mail 1d per article.
The cover has a Sunderland arrival postmark of March 27th 1909, consistent with the 16 day sailing time of the Union Castle mail Steamer to Southampton.