I thought I’d bought the wrong size at first but with a bit of wrangling I managed to figure it out.  The “back label”” doesn’t go in the middle of the back but more to one side of the back.  All tucked in and fits lovely.  It has transformed my sun bleached sofa in the conservatory and saved me money on buying a new one.  Recommend, lovely material too.  Fast delivery, even in this time of lockdown.  I will be using Wayfair again. Spot on.