That brush looks like the 'one' iv been waiting for!!
I love gardiners sill brushes but they never last long, so iv been using a tecbuk the last couple of months and they are fantastic brushes, great scrubbing and long lasting but it's not a sill brush.
The supreme brush in that picture looks like a hybrid version of a tecbuk and a sill brush, exactly the thing iv been 'fantasising' about recently
If they last longer then 8 weeks then £26 plus vat is a very good price, cheaper then both sill brushes and tecbuk, yet hopefully much better!