Felt Oil Filter Element

Three years on a new piece of information enters the arena, which could shed some light on the source of the problem, and possible reason why it happened now and not for 50 years past.

On Jul 25, 2019, Alan Wiedie in Bolton, CT, USA wrote:
"I happened to have two felt filter elements on the shelf, one appears to be a Moss part 950-570 by Classic Gold, and the other is a Crosland No. 159. I like the looks of the Crosland one better as it seems more substantial". And he included the following picture:

Filter on the left is Crosland number 159. Filter on the right is Moss Motors number 950-570. A Moss 950-010 would be "Cartridge type, felt, Crosland brand", as of 25 July 2019 listed as N/A. The Moss 950-570 is listed as "Cartridge type, felt" (Product supplied by various vendors), which means, minimally, that it is not Crosland brand. At least some of these came in a box labeled "Classic Gold", meaning it is exclusive to Moss Motors supply. Then consider that the reported failed felt filters were all procured from Moss Motors, and therein lies an implication that only parts from this single source have failed in this manner.