Gardner was appointed as a Queen's Counsel in 1960 and was subsequently admitted to the Nigerian and British Guianan bars: he also appeared in the courts of Goa, the High Court of Singapore and the Supreme Court of India, besides having an extensive practice in England.
In 1960, Gardner was appointed as a Queen's Counsel. He then became admitted to the Nigerian and British Guianan bars, and practiced in courts across various jurisdictions including Goa, the High Court of Singapore, the Supreme Court of India, and England.