John Maclean came to Demerara in 1810 as overseer, and then manager, of plantation Lusignan, where he remained until 1816. He then managed plantations Wellington, Friendship, Forbes (Berbice) and, from 1822, John Gladstone’s Vreedensloop.
He replaced Frederick Cort as attorney on the Gladstone plantations in Demerara and provided detailed information on the treatment of slaves to support Alexander MacDonnell, the pro-slavery author of Considerations on Negro Slavery .
MacLean declared that 'before the insurrection of 1823, the slaves enjoyed every comfort' and he was 'convinced that slavery was only known to them by name'.
On another occasion he wrote:
I am most particular as to punishments, food and clothing and attention to the slaves when they are sick . . . I am induced to think, from my knowledge of the Negro character, that they construe what is intended as a kind indulgence into an obligation to which they are entitled. [John Moss of Otterspool (1782--1858): Railway Pioneer Slave Owner Banker, Graham Trust (2010)]
He married Margaret Mackenzie (d of Alexander Mackenzie of Ord, Ross-shire) and the couple had one daughter, Helen, born in Grenada in 1822/3.
His widow and their daughter, Helen Mackenzie Maclean, moved to Cromarty (Scotland) where they both lived on their private incomes at various addresses, Helen until her death in 1894 [Census returns; GROS 061/00 0019].
In 1832 John Maclean (above) was executor, along with William Grant and William Campbell, of the will of Charles Maclean of Berbice [London Gazette]. It is likely that they were related, possibly brothers.