It was not long before Them was signed to Decca and they made their first recording on 5 July 1964. It was during this session that what may be their best known song, "Gloria", was recorded. They would have a top ten hit in the United Kingdom with their cover of Big Joe Williams' "Baby, Please Don't Go", the flip side of which was "Gloria". It would be followed by the single "Here Comes the Night", which went to #2 in the United Kingdom and #24 in the United States. Unfortunately, while Them met some success, tensions in the band would drive Them apart. The tensions between band members reached the point where there were two competing bands named Them, one led by Billy Harrison and Pat McAuley and another by Van Morrison and Alan Henderson. As might be expected there was a lawsuit, the ultimate result of which was that Van Morrison and Alan Henderson won the right for their band to be called "Them" in the UK. Van Morrison left Them not long afterwards and the band, led by Alan Henderson, persisted in some form until 1971. Them has regrouped since then, although without Van Morrison.
Regardless, Them would have a lasting impact on garage rock and rock 'n' roll in general. The band would have an impact on such diverse artists as The Doors, MC5, Thin Lizzy, The Saints, Elvis Costello, Nick Cave, and The Hives.
Here is a clip from 1965 of Them performing their signature song, "Gloria".