There's heaps of info about Walter and his family on the Dover War Memorial Project website, with images of documents, his English family history, local places associated, etc, based on all the research I and Simon have done over the last few years. One article is here and it has links to several others about him.
http://www.doverwarmemorialproject.org.uk/Information/Articles/Heroes/TullWDJ.htm
There are also further pages about him, which the "search" facility on the Project website will help locate. Some examples are the Walter Tull events Simon and I organised in Dover during the year-long commemorations and development of educational materials led by City of Westminster Archives, .
The two programmes are repeats from November last year. For more info, there is a new book by Phil Vasili, who first revealed Walter's remarkable story - "Walter Tull, Officer, Gentleman, All the Guns in France couldn't Wake Me". It was launched this March in Folkestone. On our "Latest News" section are references to that too, with a picture of a number of Walter's relatives, from Scotland to Kent, including Maidstone, Dover, etc.