Bottom Up Blinds? Recommended?

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I am renovating a ground floor loft apartment in SW London. Architect has suggested bottom up blinds. Are they any good? As the blind sits at the bottom of the window, does it gather dust, like a window sill does? If you have installed them do you have any recommendations for a good supplier who is well priced? Thank you!

we have this in our bathroom. The casement isn't that pretty but hides behind the bath in our setup. it will gather dust if you don't clean... but otherwise very good. can't remember supplier but was just online.

I have Luxaflex bottom up pleated blind. Tis brilliant. Privacy when needed and plenty of light. It can get dusty but hoover will suck dust up. It was made to measure. I am not in the U.K. but any Luxaflex supplier can fit them I am sure.
I don't know why they are not used more often.