The following formula works =SUMIF(Month,"<"&MonthNumber,INDIRECT(V23)) where cell v23 contains the following concatenation
="'Food Last Year'!$C" & MATCH(B$23,LYIndex,0) & ":$N" & MATCH(B$23,LYIndex,0). This gets the range I want i.e. 'Food Last Year'!$C6:$N6 where 'Food Last Year' is the...