I did a little trial and error (banging head on table) and it looks like MIN with a FILTER would be the way to go. I got round it by adding another column with IF(quantity=0,BLANK(),quantity) then used a MIN on the new column.

MinStock:=CALCULATE(MIN(Table1[Stock]),FILTER(Table1,Table1[Stock]>0))

has been suggested on another forum so this will be my way forward.

Thanks

E