Jack Beresford [formerly Jack Beresford Wiszniewski] (1899–1977), oarsman, was born at 36 St Mary's Grove, Chiswick, Middlesex, on 1 January 1899, the elder son and eldest of the three children of Julius Beresford Wiszniewski (b. 1868) and his wife, Ethel Mary Wood. His father, Julius, was taken to Britain from Poland by his governess at the age of twelve, and became a furniture manufacturer. Jack was educated at Bedford School, served with the Artists' Rifles in 1917, was commissioned in the Liverpool Scottish regiment, and was wounded in the leg in northern France in 1918. At school his sporting ambitions were directed at rugby, but prescribed physiotherapy of rowing a dinghy at Fowey, Cornwall, turned him to rowing. He then entered his father's business, and began working at the furniture factory Beresford and Hicks, of Curtain Road, London.

Beresford had an outstanding record as an amateur sculler and as an oarsman with Thames Rowing Club. He won the Wingfield sculls from 1920 to 1926, which made him amateur champion of England, and he won the diamond sculls at Henley royal regatta four times during that period. He made his international mark by winning a silver medal at the Olympic games in Antwerp in 1920, when he lost the single sculling title by one second to an Irish bricklayer from Philadelphia, John Brendan (Jack) Kelly. The two men, who in later years became friends, encapsulated the controversy of the day concerning amateur status. Before competing in the Olympics, Kelly's entry for the diamond sculls was refused. Kelly claimed that he never received the rejection letter, and the story spread that he was snubbed because, as a manual worker, the Henley stewards considered him to be a professional. Beresford, however, epitomized their view of an amateur oarsman prevalent at the time. He was sporting, displayed loyalty to his club, dressed for dinner, was well heeled, and when not in a boat was an ambassador for a gentlemanly way of life. He was fit and hardy, and a colleague remembered him as never wearing a waistcoat or an overcoat, whatever the weather. The real reason for Kelly's ban, however, was that his club, Vesper of Philadelphia, had been barred by the stewards in 1905 for sending for the Grand Challenge Cup an eight who had received payment and been supported by public subscription. Kelly's family bricklaying company built many of Philadelphia's twentieth-century public buildings. His son Jack grew up to win the diamond sculls in 1947 and 1949, and his daughter Grace became the princess of Monaco.

From the beginning of his rowing career, Beresford displayed the tactical brilliance of a winner, assessing his opponents' capabilities and pacing his training, and usually his racing, to do just enough to beat them, although he clearly possessed the killer instinct which motivates a winner and a breaker of records. 'He was very vicious in the boat,' said Eric Phelps, his coach for the Berlin Olympics. 'He would give a sickly smile to the man next to him. He never knew what it was to pack up' (private information, E. Phelps).

Beresford's successes proved his worth in every type of boat—eights, fours, pairs, and sculls—the more remarkable because his rowing weight was normally just over 11 stone and he stood about 5 feet 10 inches, light and short as oarsmen go. He won the Philadelphia gold cup for the world amateur title in 1924 and 1925, and was given the Helms award for sculling in Los Angeles in 1926. He won four further medals in the next four Olympic games: gold in the single scull in Paris in 1924, silver in the British eight in Amsterdam in 1928, gold in the coxless four in Los Angeles in 1932, and his most celebrated gold in the double sculls with Leslie (Dick) Southwood in Berlin in 1936.

The Berlin medal was Beresford's finest moment. The first five of the seven Olympic titles had gone to the Germans, under the watchful eye of their chancellor, Adolf Hitler, who was presenting the medals. Beresford and Southwood were coached by the English professional Eric Phelps, who had an intimate knowledge of the German team. He had a new, light boat built for his charges by Roly Sims in two and a half days (although it was lost in suspicious circumstances on the German rail system and turned up in Berlin only shortly before their first race) and surmised that the German crew, strong favourites, lacked the stamina to complete the 2000 metre course if put under severe pressure.

The British crew lost in the first heat to the Germans, who crossed into their lane, but qualified for the final by winning a repêchage, or ‘second chance’ round, in champion form. In the final, both crews jumped the start after observing that the starter, Victor de Bisschop, was using a megaphone so large that he could see nothing once he raised it to his lips. The British led for 500 metres, then Willy Kaidel and Joachim Pirsch went ahead. Opposite Phelps's vantage point at 1800 metres the crews were level. Southwood shouted when the Germans wandered from their lane, and then Pirsch stopped rowing. Phelps's men had rowed them down, just as he predicted. Beresford's German nickname, the Old Fox, was vindicated. It was 'the sweetest race I ever rowed in', he said. His record of rowing medals in five consecutive Olympics was unsurpassed until 2000, when Steven Redgrave of Britain won his fifth consecutive gold in Sydney.

Beresford crowned his outstanding record at Henley of two wins in the Grand Challenge Cup (1923, 1928), two in the goblets (1928–9), one in the stewards' (1932), and four in the diamonds (1920, 1924–6) by coming out of retirement with Southwood for a new event in 1939, the invitation centennial double sculls. Their famous victory in Berlin inspired the stewards to introduce this class of boat, and the Thames Rowing Club men, aged forty and thirty-six respectively, won the final in a dead heat with the Trieste double G. Scherli and E. Broschi. The Italians were European champions and much heavier and younger than Beresford and Southwood, and the Thames men realized that they would have no chance should the stewards order a re-row. As soon as they had returned their boat to its rack in the boat tent, Beresford went over to where the Italians were lying exhausted and, in a superb act of gamesmanship, cheerily congratulated them on a great race. 'Do it again in half an hour?' he is reputed to have said (private information, L. Southwood). The Italians declined profusely, and honours remained even.

In 1940 Beresford married Mary Elizabeth, daughter of Robert Craske Leaning, a medical doctor. They had one son and one daughter. This marriage was dissolved and in 1958 he married Stroma Jean Margaret, daughter of the Revd Andrew Morrison; they had two daughters.

Beresford lived at Shiplake and was often seen sculling at Henley, but always competed for Thames Rowing Club, the Putney club for which his father, ‘Old Berry’, had a distinguished record as an oarsman and coach, including winning a silver medal in the 1912 Olympic games and several Henley medals. Jack was captain of Thames in 1928–9, a vice-president from 1936 to 1977, and president from 1970 to 1977. He devoted considerable efforts to coaching and sports administration, and he carried the flag as leader of the British team in the opening ceremony of the Berlin games. He managed rowing teams on tour in South America in 1947, for the empire games in 1950, and the Olympic games of 1952. He was a rowing selector from 1938 to 1954.

Beresford was a member of the British Olympic Council from 1936 and a member of the organizing committee of the Olympic games in 1948, as well as helping to coach the double scullers Bert Bushnell and Richard Burnell, who won a gold medal. He was awarded the gold medal of the International Rowing Federation in 1947, and the Olympic diploma of merit in 1949, after helping to organize the games in London and Henley-on-Thames in 1948. He was elected a Henley steward in 1946 and was on the committee of management for many years. He was connected with the National Playing Fields Association, the Greater London and South-east Sports Council, and served on the council of the Amateur Rowing Association for thirty-five years. He was a keen swimmer and beagler with the Farley Hill beaglers, and played the umpire in the film Half a Sixpence. He was rowing correspondent of The Field from 1966 to 1971. He was a member of the court of the Furniture Makers' Guild and a liveryman of the Painters' and Stainers' Company. He was made a freeman of the City of London in 1952 and appointed CBE in 1960.

Beresford was courteous both to colleagues and to younger oarsmen, although his competitive edge in a boat occasionally spilled into arrogance when dealing with lesser mortals on the bank. When over seventy he competed in the 4½ mile scullers head of the river race. He was shaken in his last years by a tragic accident at the national schools regatta at Pangbourne in 1969. On that occasion, aged seventy, he dived into the Thames from his umpire's launch to rescue a boy who had caught a crab during a race and had been swept out of his boat. Beresford, an expert swimmer, reached the boy under the surface but had to struggle with the victim's desperate attempts to cling to him. The boy was eventually drowned. His failure to overcome the boy's plight and the tricky currents troubled him for the rest of his life. He died at his home, Highlands House, Shiplake, on 3 December 1977, the morning after presiding cheerfully over the Thames annual dinner.