Parlophone dropped him in 1942 because they wanted to use scarce shellac for Victor Silvester records. Ros credited Silvester with advice to tone down the percussion and concentrate on popular melodies: "a formula which brought him long-lasting success, at the cost of persuading the musically minded of two generations that Latin music was contentless and bland," wrote John Storm Roberts in 1979. He quickly embraced the samba rhythm made popular by Carmen Miranda, covering her hit "Tico-Tico" during his first session with Decca in September 1944 (Ros remained with the label until his 1975 retirement). The mid-’40s departure of his pianist Roberto Inglez (Scottish-born Robert Inglis, 1913-1978) was a blow to Ros; he responded by becoming a hard-nosed businessman, eventually founding The Edmundo Ros Holding Company (which embraced a publishing company, dance school, club, artist agency, etc). Ros expanded his Rumba Band to a 16-piece Orchestra including five saxes (two tenors, two altos and baritone, with doubling on flutes and clarinets), four trumpets and a seven-piece rhythm section. His 78rpm "The Wedding Samba" (1949) sold three million copies worldwide. When the mambo fad hit the UK in the early ’50s, he recruited percussionists Ginger Johnson (from Sierra Leone) and Nat Akimbo (from Ghana). In 1951 he acquired the Coconut Grove; when he eventually named it Edmundo Ros’ Dinner and Supper Club, it soon attracted an exclusive clientele including members of British and European royalty. Live BBC radio shows were broadcast overseas from the Club between 1958 and ‘61. He closed the Club in 1965 after the legalisation of gambling caused a decline in business.

Costanzo formed his own band in the 1950s that recorded and toured internationally. The first six tunes he recorded as a leader in December 1954 are compiled on Jack Costanzo Plays Jazz, Afro & Latin (Fresh Sound Records, 2005); the remainder of the anthology comprises 12 largely jazz-infected tracks made in the summer of 1956 featuring the incredible pianist Eddie Cano (1927-1988) and trumpeter Paul López (who clocked-up seven albums with Mr. Bongo) that were originally released under the title Mr. Bongo Has Brass by Zephyr Records. For his first album for Gene Norman’s GNP Crescendo label, Mr. Bongo Jack Costanzo And His Afro Cuban Band (1956) Jack deliberately emulated the trumpet conjunto format of Cuba’s La Sonora Matancera to achieve the album’s fat sound and tipped his hat to the group by covering their hit "Melao de Caña". Personnel included Cano and López, who wrote most of the arrangements. Cuban-born Kaskara (Manuel Ochoa) and Jack’s wife at the time, Ohio-born Marda Saxon, provided lead vocals. Jack went on to make second album for GNP in 1971, Viva Tirado, which he admitted, "was a turkey." Also with GNP, he sessioned on the René Touzet sets The Cha Cha and the Mambo (1955, a.k.a. The Charm of the Cha Cha Cha) and From Broadway to Havana (mid-’50s) and co-headlined with Cano and vibes player, singer and composer Tony Martínez on Dancing on the Sunset Strip (circa 1960) recorded live at Hollywood’s Crescendo club.

In 1957 Jack Costanzo and his Latin Orchestra issued the excellent Mr. Bongo Plays in Hi-Fi Cha Cha Cha on the Tops label (reissued as Mr. Bongo Plays Cha Cha Cha on Palladium in 1993), again featuring Kaskara and Marda Saxon on vocals. Between 1958 and 1961 he made a short series of albums for Liberty Records: Latin Fever, Bongo Fever, Afro Can-Can, Learn To Play Bongos and Naked City. Although the producer of the Latin Fever is credited as Ray Stanley, one of the A & R men at Liberty, Jack later revealed that it was the label’s founder Simon Waronker (1915-2005) who devised the concept for the album. Waronker instructed Jack to make an album entirely without arrangements with all the tracks jammed on the spot. Consequently Jack opted for an instrumental album giving pride of place to solos from his impressive array of sidemen, including Costanzo stalwarts Cano and López. Standout cuts include the title track, capturing Mr. Bongo’s trademark skin scorching action, and the magnificent "Malaguena", virtually an eight-minute solo by Cano. "Every time we were going to stop (recording ‘Malaguena’), in the booth was Simon Waronker moving his hand, ‘Keep playing! Keep playing!’," said Costanzo. "So you hear the record, and there are about four times when you can tell that maybe we were going to stop! And then we keep going!"

Costanzo’s session work during the 1950s included dates with the Howard Rumsey’s Lighthouse All-Stars in 1953 (collected on Mexican Passport ‘96 on Contemporary Records), Sonny Burke & His Orchestra in 1954 (compiled on The Mambo Jambo Man ‘05 on Jasmine Records), Marty Paich in 1955 (collected on Paich-ence ‘06 on Jazzcity) and with Art Pepper, Conte Candoli and others in 1958 on Mucho Calor – A Presentation in Latin Jazz on the Andex label. In 1962, Jack made the groundbreaking Latin Jazz set Costanzo Plus Tubbs: Equation in Rhythm in the UK for the Fontana label. Though the production is co-credited to Tubby Hayes (1935-1973), the revered multi-instrumentalist and bandleader only featured on two tracks. Notable sidemen included trumpeter Shake Keane, drummer Phil Seaman and flautist Harold McNair.

In 1968 Jack was signed to make the one-off album Latin Percussion With Soul w/Gerrie Woo for Tico Records after the label’s A & R man Pancho Cristal saw him perform with a seven-piece group at the El San Juan Hotel in Puerto Rico. Cristal hired the talented New York-based pianist, composer, arranger, bandleader and producer Héctor Rivera (1933-2006) to arrange the songs he and Jack selected for the project. However, when Héctor arrived in Los Angeles to conduct the recording date by Jack’s approximately 14-piece ensemble, he had only arranged his own compositions and none of the agreed selections. An enormous row ensued, but the session went ahead under Héctor’s direction and Jack later acknowledged that he was "a marvellous arranger". Personnel included Costanzo regulars Cano and López together with former La Sonora Matancera bass player Humberto Cané. It is more than likely that Tico were hoping to emulate Joe Cuba’s 1966 pop and R&B chart success with Latin Percussion With Soul, but it didn’t happen. Jack’s wife at the time, the former Playboy bunny Gerrie Woo, sang on the most dispensable of the dated crossover tracks. There are only three, or possibly four of these, the rest of the material comprises of swinging mambos and fusion a la Mongo replete with solos and a guajira; the highlights being the Héctor Rivera compositions "Recuerdos", "Mambo Jack", "Mantequilla" and "Que Vengo Acabando", Booker T’s "Green Onions" and the Nat Adderly standard "Jive Samba".