After a successful run in European F3 in 1965-66, he was signed by Ferrari. He competed in one Grand Prix and one F2 race before being casually discarded.
Born in Cairo in 1942, Williams was based in Italy for much of his racing career. It had looked likely that he was destined for a career in engineering untill he was waylayed by his friends, which included Piers Courage, who used to meet at a South Kensington pub. Jonathan and Piers became best friendsand they would occasionally meet up at a local airfield for some illicit racing, Jonathan with his Mini and Piers with his mother's Morris Minor Traveller.
Jonathan did some club racing and had a season of European F3 under his belt when Piers quit school and escaped to Jonathan's flat in Harrow, North London, which he shared with fellow racer John Chrichton-Stuart.
They bought a pair of Lotus 22s and decided to do a season of F3 together on the continent in 1964 calling themselves Anglo-Swiss Racing, using Lausanne as a base.
Living from hand to mouth, they used their start money to live a hand to mouth existance travelling from round to round. It was then that they met up with Charles Lucas and the three teamed up, with Jonathan and Piers driving the Brabhams which Lucas had aquired. For Piers it was the start of his rise to fame and F1 while Jonathan stayed in F3 driving for de Sanctis in the Italian Championship and enjoying considerable success.
Then in the Autumn of 1967 he received a call from Ferrari and was plucked from relative obsurity to drive in the Mexican Grand Prix. He qualified 16th some 6 seconds slower than his team leader Chris Amon and finishing 8th in the race a full 2 laps behind Jim Clarks in the winning Lotus 49 DFV. His career as a Ferrari works driver included that one GP, a single F2 race in a Ferrari 166 at Rouen and a handful of sports and Can-Am outings, which included Le Mans and the BOAC 500.
He was then dropped and spent the rest of his driving career scratching around for drives. A an abortive Formula 1 project for Abarth was followed by some Formula 2 in 1968 when Piers, now an F1 driver, persuaded Frank Williams into signing Jonathan for his F2 team, winning the Rhine Cup. He then raced the works Serenissima and various other privateer sports cars into the early seventies before retiring to pursue a career as a pilot based in the south of France.
In 1970, Courage was offered a drive at Ferrari but he declined perhaps his friend's experience had played a part and how different things might have been had he accepted.