[2] In 1757, Alleyne was elected for the Parish of St. Andrew to the Parliament of Barbados, a seat he held for the next forty years, with only a break in 1771.
[3] Already after a decade in the Parliament, he became Speaker of the House of Assembly of Barbados, serving until 1770 and after another two years was reappointed until 1779.
[4] Despite being a slaveowner, Alleyne publicly voiced opinions unpopular to the planter class at that time, declaring in the House of Assembly that he disapproved of the system of slavery, "an unhappy sight which leaves an immense debt upon us to clear the obligation of human nature".
[5] Alleyne was created a baronet, of Four Hills, in the Island of Barbados on 6 April 1769.
[7] In 1770, Alleyne financially laid the groundwork for establishing The Seminary, a school for "the maintenance, support, and education of poor boys".