Aztecs - The Hoax Is Over, recorded in September 1970

In 1969 Thorpe decided to try England, after being offered a recording deal by the Australian-born, London-based impresario Robert Stigwood, who had risen to become manager of The Bee Gees and Cream. While rehearsing a backing band in Melbourne that would form the basis for a new Aztecs, the guitarist unexpectedly dropped out, leaving Thorpe to assume lead guitar role at short notice. It marked another turning point in his career and from this point on Thorpe played lead guitar in The Aztecs as well as continuing as lead vocalist. His planned six-week stay in Melbourne soon stretched into months and eventually Thorpe decided to remain in Australia and re-launch his career.

Thorpe himself openly acknowledges that this new 'heavy' version of the Aztecs owes much to 'guitar hero' Lobby Loyde. Lloyde already had a cult following due to his stints in two of the most original Australian bands of the 1960s, The Purple Hearts and Wild Cherries. While his stint in the new Aztecs was short (from December 1968 to January 1971), his musical influence proved crucial in steering Thorpe in a completely new direction, and he strongly encouraged Thorpe to keep playing guitar.

The new Aztecs' blues-based heavy-rock repertoire was dramatically different in style from the original group, and they quickly became famous (or notorious) for the ear-splitting volume at which they played. Thorpe had also drastically changed his appearance—he grew a beard, often wore his now shoulder-length hair braided in a pigtail, and he had long since traded the tailored suits for jeans and t-shirts. Needless to say this did not endear him to people who came to the shows expecting the 'old' Billy Thorpe of the "Poison Ivy" era, and this led to sometimes violent confrontations with disgruntled fans and promoters.

Their breakthrough recording was an ambitious album, The Hoax Is Over, recorded in September 1970 with new drummer Kevin Murphy. The album was an unequivocal signal of the Aztecs' new direction, containing only four tracks, three of which were Thorpe originals. The LP is dominated by two extended tracks: a version of Johnny "Guitar" Watson's "Gangster Of Love", which clocked in at 24:35 and ran the entire length of Side 1 (an unprecedented move in Australian pop music) and Thorpe's own "Mississippi" which ran 19'35". According to Thorpe, the band (which at this time comprising himself, Murphy, pianist Warren Morgan, guitar legend Lobby Loyde and bassist Paul Wheeler), were all high on LSD and jammed continuously while engineer Ernie Rose just let the tapes roll. The result heralded the fully-fledged arrival of the new Aztecs and live shows at Melbourne venues consolidated the band's reputation and drew enthusiastic responses.