▁Africa , ▁defence ▁costs ) ▁or ▁rein vest ment ▁of ▁prof its ▁back ▁into ▁the ▁slave ▁trade , ▁the ▁total ▁prof its ▁from ▁the ▁slave ▁trade ▁and ▁of ▁West ▁Indian ▁plant ations ▁amount ed ▁to ▁less ▁than ▁ 5 % ▁of ▁the ▁British ▁economy ▁during ▁any ▁year ▁of ▁the ▁Indust rial ▁Revolution . ▁Eng erman ' s ▁ 5 % ▁figure ▁gives ▁as ▁much ▁as ▁possible ▁in ▁terms ▁of ▁benefit ▁of ▁the ▁doubt ▁to ▁the ▁Williams ▁argument , ▁not ▁sole ly ▁because ▁it ▁does ▁not ▁take ▁into ▁account ▁the ▁associated ▁costs ▁of ▁the ▁slave ▁trade ▁to ▁Britain , ▁but ▁also ▁because ▁it ▁car ries ▁the ▁full - emp loyment ▁assumption ▁from ▁econom ics ▁and ▁holds ▁the ▁gross ▁value ▁of ▁slave ▁trade ▁prof its ▁as ▁a ▁direct ▁contribution ▁to ▁Britain ' s ▁national ▁income . ▁Histor ian ▁Richard ▁Par es , ▁in ▁an ▁article ▁written ▁before ▁Williams ' s ▁book , ▁dismiss es ▁the ▁influence ▁of ▁wealth ▁generated ▁from ▁the ▁West ▁Indian ▁plant ations ▁upon ▁the ▁finan cing ▁of ▁the ▁Indust rial ▁Revolution , ▁stating ▁that ▁whatever ▁substantial ▁flow ▁of ▁invest ment ▁from ▁West ▁Indian ▁prof its ▁into ▁industry ▁there ▁was ▁occurred ▁after ▁em an cip ation , ▁not ▁before ▁it . ▁ ▁Wh igg ish ▁history ▁and ▁the ▁civil ising ▁mission ▁ ▁Thomas ▁Bab ington ▁Mac a ul ay ▁( 1 8 0 0 – 1 8 5 9 ) ▁was ▁the ▁for em ost ▁historian ▁of ▁his ▁day , ▁arg uing ▁for ▁the ▁" Wh ig ▁interpretation ▁of ▁history " ▁that ▁saw