Agree Roman blinds outside the recess would be perfect.

It's autumn, not winter. Yes to Roman blinds 😉

Try shutters, shouldn’t be too expensive for a small window.

You could try perfect fit blinds also known as intu blinds or directories blinds. 

They fit into the window frame and don't take much light off. They are easy to fit. We've had these a few years now and they've  been a great solution.

It should have said directorder blinds.

I have both perfect fit and intu blinds. They are different. Intu don't have the external frame

We have perfect fit pleated thermal blinds- don’t take up much space on the window frame and keep in the heat well.

Roman blinds outside the recess are fine. If you hang them quite high above the window they don’t cut out the light when they are open.

Hi S Z, roman blinds would work well, they look smart and are timeless. You could opt for a self stack rather than a waterfall stack it would block less light.

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