If the engine revs increase without the speed of the wheels increasing (no nasty graunching noise from the gearbox, no squealing of tortured rubber from the tyres, and the speedo reading stays constant or only increases 'normally'), then there is a problem with the clutch.
If the clutch pedal is very high, it could be something to do with that.
Failing that, I am afraid that you are down to actual clutch problems. There is a possibility that oil/fluid is getting on to the clutch plates, but the more likely thing is that the clutch material has worn and the clutch needs replacing. I think I can safely describe this job as a bit of a pain, so the labour charge will be significant.
I don't know where the best place to go is, but Ford will be expensive.