bˈɛkɪt wʌzɐ kˈiː fˈɪɡjɚɹ ʌv ɪmpˈoːɹtənt ɡɹˈuːps ɪnðə bɹˈɪɾɪʃ fɹˈiː dʒˈæz slˈæʃ ˈɪmpɹəvˌaɪzd mjˈuːzɪk sˈiːn, ɪŋklˈuːdɪŋ ˈiːən kˈɑːɹz nˈuːklɪəs, ðə bɹˈʌðɚhˌʊd ʌv bɹˈɛθ ænd ðə dˌɛdɪkˈeɪʃən ˈɔːɹkᵻstɹə, lˈʌndən dʒˈæz kəmpˈoʊzɚz ˈɔːɹkᵻstɹə, lˈʌndən ˈɪmpɹəvˌaɪzɚz ˈɔːɹkᵻstɹə, dʒˈɑːn sɚmˈænz ɑːktˈɛt, dʒˈæŋɡoʊ bˈeɪts, ɹˈɑːni skˈɑːts kwɪntˈɛt, kˈæθi stˈoʊbɑːɹt, tʃˈɑːɹli wˈɑːts, stˈæn tɹˈeɪsiz bˈɪɡ bˈænd ænd ɑːktˈɛt; ˈɛltən dˈiːnz nˈaɪnsɛns.
Beckett was a key figure of important groups in the British free jazz/improvised music scene, including Ian Carr's Nucleus, the Brotherhood of Breath and The Dedication Orchestra, London Jazz Composers Orchestra, London Improvisers Orchestra, John Surman's Octet, Django Bates, Ronnie Scott's Quintet, Kathy Stobart, Charlie Watts, Stan Tracey's Big Band and Octet; Elton Dean's Ninesense.