One of Postans' varieties--indeed, his first, it seems--is . . . 'May Quennell'. Perhaps there are two wheels spinning here, a romantic link between Postans and the Quennell family, and rose breeding amateur Dr. Quennell funneling his seedling through the more-established Postans to William Paul.
I am sure you are correct about the romantic connection. The question is, who bred ‘Lord Bacon’, Postans or Quennell? Easlea said in 1910 it was Postans. In 1943 he said it was Quennell. We have Postans’ varieties: 1878 May Quennell 1879 Countess of Rosebery 1879 Duchess of Bedford 1881 Lady Sheffield 1881 Red Gauntlet, and then there is 1883 Lord Bacon.
What about if I change the breeder from Paul to Postans temporarily until further information comes to light?
Yes, I think Postans is at least closer to being the breeder than is W. Paul. Postans is Richard Broadhurst Postans, also of Brentwood (I keep slipping and saying "Brentford"); I see he was quite a naturalist. He also bred Zonal Geraniums. Quennell meantime was an ardent rose exhibitor, as one finds examining the horticultural press of the time.