Stuck in first or reverse

Hi, I have Defender 90 TD5 with 41,000 on the clock. When I put the car into fwd or reverse the clutch pedal stays down and the car moves off. I can't get it out of gear untill the engine stalls. This does not happen all the time, but is becoming more frequent. It does not seem to matter if the engine is hot or cold.

Took it to a garage and they reccomend changing the clutch. V expensive. Is it a problem with the clutch or something else like the clutch fork? I dont know much about any of this and need reliable advice. Help much appreciated

I had the same thing on my disco a few years ago, it sounds like the clutch fork has failed, thats why the pedal is staying on the floor.

Not a major job to do but while the gearbox is off you may as well fit a new clutch and heavy duty clutch arm

Thanks, Just want to ensure that they fix the problem and dont just replace the clutch and leave me with the same problem.