In 1948 Gilbert founded the Wigmore Ensemble which brought together leading wind players of that generation including Jack Brymer, Terence MacDonagh and Gwydion Brooke. Dennis Brain played regularly with the ensemble, until his death in 1957. Gilbert's range embraced jazz and dance music: concurrently with his orchestra work he was Geraldo's flautist. In the concert hall Gilbert gave the British premieres of concertos by Ibert, Nielsen and Jolivet. In 1948 Gilbert joined the BBC Symphony Orchestra under Sir Adrian Boult. Sir Malcolm Sargent succeeded Boult as chief conductor in 1950; a professional disagreement with Sargent led to Gilbert's resignation in 1952. He rejoined Beecham, now with the Royal Philharmonic Orchestra, in 1957. In 1960 Eugene Ormandy unsuccessfully sought to appoint Gilbert to the principal flute position in the Philadelphia Orchestra; Beecham died in 1961 and Gilbert concluded, "after the loss of Sir Thomas from the musical world I no longer felt that I wanted to be a regular member of a symphony orchestra except perhaps an odd performance as a guest artist"; he never again played regularly with any other orchestra though he was the guest principal with the London Symphony Orchestra on occasion.