They measure 49.5 x 42 inches,

As you can see in pic 2 you pull the chain & they fold up, but the other blind does not have the plastic bit (pic 3)to pull the blind up however I do have the chain.

So its the second blind of which you have to work out to get working.

Perhaps you can show a curtain shop & ask them do they have the plastic part (pic 3) & if they do, fit it on & insert chain,

I was told these cost over £350 so my price is great considering that they are in really good condition, 

I am not sure what they are made of.