After graduating, Schapiro joined the family horse trading and meat business and worked there until his forties, when he retired to capitalise on his love of gambling by becoming the banker of a baccarat syndicate at Crockford's gaming club in London.
In 1935, while he was working in Hamburg, his fluency in German led to his being chosen as the interpreter for Viscount Castlerosse when the latter travelled to Berlin to research an article for the Daily Express.
He also represented Britain in the 1964 Olympiad and the Bermuda Bowl of the same year, which was played early in 1965, and in ten European Bridge League national teams championships, winning in 1948, 1949, 1954 and 1963.
In the 1965 Buenos Aires Bermuda Bowl, B. Jay Becker noticed Schapiro and his partner, Terence Reese, holding their cards in unusual ways during bidding, the number of fingers showing indicating length of the heart suit.
A number of players and observers, including Dorothy Hayden, New York Times columnists Alan Truscott, John Gerber, British nonplaying captain Ralph Swimer, British Bridge League Chairman Geoffrey Butler, ACBL president emeritus Waldemar von Zedtwitz, and ACBL President Robin McNabb, all watched Reese and Schapiro and were convinced that they were signalling illegally.
The British Bridge League (BBL) subsequently convened their own enquiry, chaired by Sir John Foster, barrister and Member of Parliament, and General Lord Bourne.
In 1968, a compromise was reached, the WBF maintaining their guilty verdict, but allowing Reese and Schapiro (who had announced his retirement from international bridge after the Buenos Aires Olympiad) to play in future world championships.
Truscott's book emphasizes the unlikelihood of the observed variations in finger signals being coincidental, or of such a large number of witnesses colluding to fabricate the evidence.
In May 2005, the English journalist David Rex-Taylor, a bridge player and publisher, claimed that Reese had made a confession to him forty years earlier, one that was not to be revealed until 2005 and after he and Schapiro were dead.
Schapiro's 90th birthday party in London was attended by Jaime Ortiz-Patino, the WBF President Emeritus and the owner of Valderrama Golf Club, who had been a witness for Reese and Schapiro in the BBL enquiry; Omar Sharif, the Egyptian film star and bridge player; Prince Khalid Abudullah of Saudi Arabia, a family friend; and many personalities from the bridge and casino worlds.
Dimmie Fleming – another international player and the only woman to play on the British open team – defused the situation by signing next, drawing an upwards arrow and writing, "But will he ever be adult?
"[11] Another story shows his partner Terence Reese picking up a collection of silver cup trophies from Schapiro's flat in Eaton Place (the Upstairs, Downstairs setting) and carrying them in a pillow-case.
Stopped in the street by a policeman and asked to explain his unusual sack of possessions, Reese led the officer back to the flat so that Schapiro could validate his explanation.