The car would run for any period of time without any coolant leak, but when parked after a run, then a significant puddle ensued! This appeared to be limited to the front R side ( approx 1/3 of the RHS ) and lots of the lower car parts were wet. Eventually I found that there was no leak while traveling, only while parked!. Eventually I found the leak…it was the (plastic ) coolant resevoir…on the R rear corner , there was a coolant leak …a single spray line about 1/4 mm . This the second coolant resevoir to leak . Also a few years ago I had significant coolant leaks in other parts of the coolant plumbing in the vicinity of the thermostat. Jaguar surely has made a bad choice of plastic for coolant applications !?
15-20 years is the usual lifespan of glass fiber reinforced Nylon as used in all modern cars. The temperature and pressure (and maybe the fluid level)? is the highest after a run which is probably why it leaked only then.