Was not sure you meant to include Mckenzie Guyana as well?
Behoort? de carte generale & particuliere d' Essequebo et Demerare par F. von Bouchenroeder? 1798
DE MAHAICA A DEMERARIE
Plantation Owner Area Produce
Twoo Friends Lot 41 Mc. Kenzie C
Lufignan Lot 39 Mc. Kenzie 500 C
Pursuant to Ordinance No. 18, of the year 1851, His Excellency the Lieutenant-Governor is pleased to order the following List of Justices of the PEACE for the Colony of British Guiana, residing in the Counties of Demerara, Essequebo, and Berbice, respectively, to be Published for General Information:-
COUNTY ESSEQUEBO William Duncan M'Kenzie,
Planter Arabian Coast
Guiana Public Buildings, 2nd January, 1854 By Command W.B. WOLSELEY, Acting Government Secretary.
The following indexes only give the name and the year the name is mentioned:
BDM indexes-The Colonist Newspaper,Georgetown, BG 1864-1880
Braithwaite is listed in 1878
McKenzie, 1869, 72*, 73, 74, 77-79
Died - Monday 15, 1872* p 2 col 2 The Colonist
McKenzie - At his residence, Camp Street, Alexander McKenzie, aged 27 years (I happen to have this one entry.)
BDM Index -The Argosy Newspaper, Georgetown, BG 1880-1896,
Brathwaite/Braithwaite is listed 1880, 86
McKenzie 1888, 89, 92, 93
The British Museum Newspaper Library at Colindale, London has the microfilms for these newspapers.