Yes, it was in 1973 when driving along the old A21 towards Sevenoaks, during the early afternoon.
Bright, clear visability, with a friend in the passenger seat, we both witnessed a black round ball, with what looked like spikes / fins coming out of it of equal length on top, at the sides, and on the underside. Completely silent and stationary about 1000 feet to the West of the road, we approached it but before arriving at about 1/4 of a mile away from the object it hurtled away into infinity in three seconds without a sound.

No, it was NOT a Harrier Jump Jet, or a helicopter (both of which I have frequently seen), nor anything that could be logically explained.
UFO, extra terrestorial or terrestorial (USAF or RAF experimental craft), who knows? But, yes I do believe we have aquired some of the advanced technology associated with "visiting" space craft since the Second World War.
I have also positively witnessed at least one ghostly apparition, and been present at possibly another, but that's another thread! 8-) 8-)