Triumph Repair: Spitfire clutch requires pumping and still slips, clutch pedal, clutch disc

Question
I have to pump the clutch on my 1975 Spit 1500 to allow me to get the car into gear. Once in gear, when I release the clutch it seems like the drive axle barely engages and I can feel slippage.

Do you think this is two separate problems or two manifestations of the same problem?

Is it maybe that the need to pump the clutch pedal is indicative of one problem (that the system needs bleeding or the clutch master needs rebuilding or replaced?) and the clutch slipping is an altogether separate problem (like maybe that the clutch disc has worn out and needs replaced?)

I did notice that both problems started after I took a fairly long drive of about 100 miles a while back. Near the  end of the trip (last 10 miles or so), I started to notice that the engine would rev when I had constant pressure on the gas pedal. I realized that what was happening was that the clutch was becoming disengaged and the engine was able to rev freely until I let off the gas and the clutch would re-engage. As I was coming off the highway, I realized that  it seemed like the trans was stuck in gear, necessitating that I pump the clutch pedal up to build up enough pressure to allow me to change gears. So, I basically limped the car home and parked it.

Is there maybe an adjustment that I can make to get a few more miles out of the clutch before having to replace it (if that's the solution?)

Thanks very much for your expertise.

Answer
Hi Charles,
Yes, you could have two problems, Clutch burned up and slipping and master cylinder bad too. A bad master cylinder can usually be tested by starting the engine and pump up the pedal until you can put it in gear then just sit there for a minute or two with the engine running and in gear and pedal down. A bad master cylinder will usually bleed down and the car will slowly start to creep as though you are letting the pedal up. If not, you may just have a pressure plate & disk burned up. However, it is good to replace all clutch parts when you put in a new clutch. Pilot bearing, clutch release bearing, pressure plate and disk. You can decide later if you want to replace the master cylinder & slave cylinder since they can be replaced from the outside. Use DOT 4 fluid.
Howard