Summing Difficulty - Linking Data based on Condition

Hi,

I'm having difficulty trying to sum data based on a condition. This is normally an easy SUMPRODUCT() function, but the difficulty is created by the multiple locations of the data. The data is linked by an ID.

In the sample sheet attached, I have three worksheets, "Shop Info", "Item Details" and "Summary".

The "Shop Info" tab has a "Shop ID", "Shop Floor Area", and "Shop Location".

The "Item Details" what is sold by the shop, the colour and quantity. It has a shop ID that links the item to the Shop ID on first sheet.

In the summary, I want to sum all the quantity of the items in the shops by location, but only if the shop floor area is greater than 150. This is where I'm stuck.

The text in green should be the right answer.

All help appreciated.
Figs.