▁the ▁fields ▁that ▁would ▁be ▁cultiv ated ▁by ▁local ▁pe as ants . ▁These ▁pe as ants ▁would ▁pay ▁rent ▁to ▁the ▁land owner ▁either ▁through ▁agricult ural ▁labour ▁on ▁the ▁lord ' s ▁dem es ne ▁fields ▁or ▁through ▁rent ▁in ▁the ▁form ▁of ▁c ash ▁and ▁produce . ▁By ▁the ▁ele vent h ▁century , ▁a ▁market ▁economy ▁was ▁fl our ishing ▁across ▁much ▁of ▁England , ▁while ▁the ▁eastern ▁and ▁southern ▁towns ▁were ▁heavily ▁involved ▁in ▁international ▁trade . ▁Ar ound ▁ 6 , 0 0 0 ▁wat erm ills ▁were ▁built ▁to ▁gr ind ▁fl our , ▁free ing ▁up ▁labour ▁for ▁other ▁more ▁product ive ▁agricult ural ▁tasks . ▁ ▁Although ▁the ▁Norman ▁invasion ▁caused ▁some ▁damage ▁as ▁soldiers ▁lo oted ▁the ▁coun tr ys ide ▁and ▁land ▁was ▁conf isc ated ▁for ▁castle ▁building , ▁the ▁English ▁economy ▁was ▁not ▁greatly ▁affected . ▁Tax es ▁were ▁increased , ▁however , ▁and ▁the ▁Norm ans ▁established ▁extensive ▁for ests ▁that ▁were ▁explo ited ▁for ▁their ▁natural ▁resources ▁and ▁protected ▁by ▁royal ▁laws . ▁The ▁next ▁two ▁centuries ▁saw ▁huge ▁growth ▁in ▁the ▁English ▁economy , ▁driven ▁in ▁part ▁by ▁the ▁increase ▁in ▁the ▁population ▁from ▁around ▁ 1 . 5   mill ion ▁in ▁ 1 0 8 6 ▁to ▁between ▁ 4   and ▁ 5   mill ion ▁in ▁ 1 3 0 0 . ▁More ▁land , ▁much ▁of ▁it ▁at ▁the ▁exp ense ▁of ▁the ▁royal ▁for ests , ▁was ▁brought ▁into ▁production ▁to