Eilert Ekwall
Eilert Ekwall was the author of The Concise Oxford Dictionary Of English Place-Names - 1960. This book is available from major booksellers and can also be read for free on the Internet archive.
I have extracted the entry for the Belchamps below which includes Belchamp Walter. Interestingly origin of the interpretation of the part of the village name, balca - bezlc - belce, meaning a roof made of beams.
In addtion there is an apparent reference to a date of 939, which is close to 940, these could be a jumbled 904 that appears on the Village Millenium Sign.
The derivation of the Walter part of the village name is also repeated here and attributes it to the "holding" of the village in 1297. I can find little other evidence of Walter de Tey in other histories of Bechamp Walter as being associated with the village. I think that the Walter is more likely to be attributed to Walter de Beuachamp.
The entry from The Concise Oxford Dictionary Of English Place-Names for the Belchamps:
Below is the listing from the dictionary:
The Walter de Tey connection
This seems to be a complicated one that is not well documented. There seems to be a marriage between a de Beauchamp and a de Tey in the 13th century and the de Beauchamps were definitley associated with the region at that time.
See my page on John de Steyngreve for more details on this connection. It must be born in mind that this was the 13th Century and I am also taking my research from Thomas Wright's History of Essex 1831/36. Ekwall does mention a William in relation to Otto, as in Belchamp Otton.