GTV speedo

During todays amble around the leafy lanes of wales my speedo started to fluctuate after an hour it now reads nothing at all,
anybody any ideas??????

as i understand it early gtvs speedos were cable driven off the gearbox and later types are functional as a result of the average value of the 4 abs sensors if your abs light has not come on due to an abs fault which would then stop your speedo working odds are its a broken cable undo the cable off the top of the gearbox turn the inner cable by hand and have someone inside the car see if the needle flickers at all