Think Art can claim to have the only airworthy civilian Harrier!
Two Harriers currently registered in the UK since August 2019, G-RNFA/ZH803 Sea Harrier FA2 and G-RNTB/ZD990 a Harrier T8. Owned by Fly Harrier Ltd, presumably there is/was an intention to fly them...
HSA also had a GR1 registered at G-VSTO in the early 70s for a demo tour in Switzerland. Several more registered in the UK and US and subsequently cancelled, NASA supposedly had a couple of AV-8s