Casey learned to play the saxophone while in the army and formed the Seniors late in 1959. They appeared regularly in and around the Liverpool area at venues including the Jacaranda. The owner of this club, Allan Williams, booked them for the Liverpool Stadium Show with American rock 'n' roller Gene Vincent in May 1960. Their performance was witnessed by London impresario Larry Parnes who was impressed and asked Williams to arrange an audition as he was seeking bands to back his stables of artists, such as Billy Fury, Johnny Gentle and Duffy Power.

Following the audition, the Seniors were booked by Parnes to back one of his artists for a season in Blackpool. As a result, they turned professional. When the season was cancelled, Casey confronted Williams who promised to take the group to London and find work for them. He took them to the famed 2 I's coffee bar where, as luck would have it, the German club owner Bruno Koschmider was present seeking bands for his Kaiserkeller Club. Koschmider booked them for a season starting at the end of July 1960. The residency ended in early October and they tried to find other work but they ran out of money and had to be repatriated. On their return to Liverpool they lost all their equipment when the building they were storing it in burned down.

They re-grouped in January 1961 with Frank Wibberley replacing Wallington on drums and the addition of a second vocalist, Freddie Fowell (the future Freddie Starr) and secured a recording contract with Fontana.

They suffered financial difficulties and disbanded in December 1961. Casey launched the group again early in 1962 with tha same line-up apart from Paul Whitehead who was replaced by two bassists, Frank Bowen and Lou Walters.

They appeared at all the major Liverpool venues, but despite releasing three singles and an album, rarely ventured outside the north-west of England.

Howie Casey & The Seniors finally disbanded for good in June 1962. All the band members moved on to other groups. Lou Walters joined Rory Storm & the Hurricanes, Frank Bowen joined Lee Curtis & the All Stars, Derry Wilkie fronted the Pressmen, Frank Wibberley joined the Lee Eddie Five, Freddie Fowell formed Freddie Starr & the Midnighters, Brian Griffiths joined the Big Three, Howie Casey himself joind Kingsize Taylor & the Dominoes and later became a sought-after session musician.