Hi all recently aquired a lovely s type bought as a non runner only has 80k miles.
key opens doors and unlocks steering lock etc but will not crank, ive had the power probe on the starter relay and engine turns over freely but will not start off the key any help much appreciated

 

Do you have the clutch pedal depressed? Not positive, but am pretty sure there’s a position switch that be closed before the starter will operate. Don’t know if there’s also a transmission neutral switch in the same circuit, but play with the shift lever and see if there’s any difference.

Next, look at the security system light on the top center of the dash, near the base of the windshield. Here's how the light is supposed to behave if all is good and no faults are present:

First, lock the car with the key fob. Press the lock button a second time to set the alarm system. The horn should chirp once. Watch the little red light. It should flash once every few seconds or so to show the system is armed. Now press the key fob unlock button twice to unlock all the doors. The red light should go out. Now hop in the driver's seat and turn the key to RUN (Not start yet). The red light should come on solid ONCE for about 3 seconds and then go out. If it flashes anything after that, you've got a stored fault and the security system may have inhibited the starter.

 

Some of the cars don't chirp or need double presses but just find what works

 

Did you check the inertia switch?