Sickert, Cornwall, and paper.

Basically paper is made by crushing wood pulp, sending the slip through rollers, drying on racks and imprinting a watermark – or not. Drying and cutting is the end of the process, which part of this manufacture is Patricia Cornwall suggesting was limited to a thousand sheets?
The dryings racks, pulp, cutting, or watermark?
The drying racks would leave marks on the paper, would be an expensive item for a manufacturer to purchase, and expected to last five years. A watermark could be commissioned by an artist or anyone, but it’s a bulk order of ten thousand or more – the size of a bucket of pulp. The nature of the pulp perhaps? That would take forensic examination of  all likely paper – i.e date range, cut size, and geographic region, produced, discovered and recovered in the last one hundred years. So how many sheets of Victorian paper did Patricia Cornwall compare? A thousand?
Well, that explains that theory.
To which “Jack the Ripper’ letter is Sickert’s handwriting compared? If we take the most likely, the Dear Boss letter, it bears no comparison to Sickert’s writing.