>>I live in the UK and there was a documentary on last night about the Congo - the narrator was walking with a group of the Pygmy tribe when they came across a snake they called the "Yellow Mamba". Is this a local name given to a different type of snake???
Most likely they were talking about a yellow color phase of the WA green mamba (Dendroaspis viridis) or Jameson's mamba (D. jamesoni), which can sometimes be a yellow coloration. To see some pics of some very yellow WA greens, check out Richard Mastenbroek's elapid pages, I think it's http://www.kingsnake.com/elapid. At least with D. viridis, most of them have a 'fade to yellow' effect with their tails (mine certainly does). If that link I provided didn't work, just do a search for his page, I'm sure you'll find it.