Once you've taken the 10mm bolt out of the egg shaped plate at the base of the speedo cable, put a small screwdriver aside it and tap it to one side, if at this point it won't twist from side to side and pluck out. Then you will have to place the screwdriver between the cable plate and the gearbox housing and tap it gently untill they begin to separate.
I know there really isn't much room to work in there but it's do-able.