Solver add-in linear programming problem

Hi Alf, thanks for this, but there is a problem in that the 16 units produced in quarter 2 incur holding cost twice, both in quarter 2 and 3 so it is actually cheaper to not meet demand in the final quarter and incur costs of £7 rather than the £12 per unit that it is costing to hold the 16 units produced in quarter 2. I have uploaded a new spreadsheet where i think the total cost is less than on your spreadsheet.