Hi, I also have some von Tunzelmann's in my family, although not in my direct line. Specifically an Edward W. who was born in London in ~1861. At the time of the 1871 census he was living in Guernsey with his mother, who was Russian and a Doctors wife. He married in 1891 Maud Bateman who was my great-great grandmothers sister. If this is a link then a) I'd be interested to here from you and b) what I have so far is here;
http://www.tla-net.demon.co.uk/family/254.htm