There are two grades of watercolour paper from Winsor & Newton. One's the Artist's Water Colour Paper and the other is Cotman.
Even though it's not so called Artist quality, it's still quite expensive, compared to the student grade Daler Rowney Aquafine watercolour paper that I use often.
The edges are gummed down to prevent stretching and warping when water is applied, and it works really well.
There are also pads that are not gummed down, such as the spiral pads. You can buy them as single sheets as well.
The Cotman watercolour paper is 300gsm cold press/NOT, grain fin. The textured surface is slightly smoother than the Daler Rowney Aquafine watercolour paper.
Winsor & Newton on its website say it has a natural warm white surface. When I compare to the Aquafine watercolour paper, it does indeed feel warmer but the difference is only visible when compared side by side.
The smooth surface takes water very well. It's durable and can take several layers without the paper fabric coming off. This aspect is superior compared to the Daler Rowney paper
The quality of the paper is great and I love using it.
Cotman watercolour paper blocks are available at most art supplies store.
Here are more sketches done on this paper.