You can read more about it here:
My original watercolour tests on the paper
I really enjoyed using this paper and really didn't need to make any adjustments to my painting technique.
Now for an update:
I have been in touch with St. Cuthberts Mill regarding the paper and enquired when it would be available. Here is the reply:
'We have exhausted the supplies of our old HP surface in 300gsm, 425gsm and 638gsm, so the sheets in the improved finish (Similar to the samples you trialled) should be available from next month.
Certainly R K Burt will have some.'
(R K Burt Ltd are wholesale paper suppliers)
So it sounds as though the original surface of the paper will be no more. Personally, I found that the latter gave the surface a little too much texture for my liking, so I look forward to the smoother surface.
As an addendum:
I have since spoken to Mr Clifford Burt at R K Burt Ltd, and he says that they are soon to receive the new stock, but that it is likely to be a few months before it is readily available, as shops and suppliers will have to sell their stocks of the previous Saunders Waterford HP.
We had a very interesting conversation in regard to the availability of a decent British made HP paper and they feel that this new surface will prove to be very popular and is long-awaited. His opinion was that Fabriano had provided the smoothest HP watercolour paper up until now.
The R K Burt Ltd website is worth a look at, particularly the pages about their history.