Speedo not working and battery light on?

Hi folks,
I wonder if anyone can help... My girlfriends ford ka has got a similar problem to that that's been reported by some of you. Basically the battery light is on in the car and won't go out and also the speedo fails to move from 0, that's until you turn the engine off at which point the speedo and fuel dial needles flicker! Battery and alternator checked for functionality and both ok.
Any advice at all would be muchly appreciated. Not really bothered of the battery light stays on as long as I can get the speedo to work. (ALL FUSES CHECKED AND OK)
Please email me at ph1lw990 at hotmail do co dot uk.

Many thanks in advance to all.
Phil