These helmets were actually Egyptian, they were made in England for use by the forces of the Khedive of Egypt. In the mid to late 1800s Egypt was modernizing their military, they hired European and American military advisors and started using several types of European made armor, first these helmets with split ring camail and split ring mail shirts from England and then later a French made helmet with butted link camail and a steel cuirass.
The Sudanese ended up with Egyptian armor by capturing it or by buying or trading for it. A lot of Sudanese armor, weapons and accessories were captured and sent to England after battles with the fanatic Islamic revolutionaries of the self proclaimed "Mahdi" in the late 1800s.
Here are a couple of links with information on the Khedives and the Sudanese.
http://www.vikingsword.com/vb/showthread.php?t=16920
http://www.ottoman-uniforms.com/egyp...820-till-1914/
http://www.pinterest.com/samuraianti...ives-of-egypt/
http://www.themailresearchsociety.er...tmrs_pdf_9.pdf