Inspiration
It is generally assumed that Robert Browning was A.S Byatt's poetic inspiration for Randolph Henry Ash.
Even from the beginning the novel alludes heavily to Browning's poem 'The Ring and the Book'. Roland's discovery of the letter in Ash's copy of Vico is described intimately by Byatt
"Its boards were bowed and creaking; it had been maltreated in its own time. Its spine was missing, or rather protuded from amongst the leaves like a bulky marker."
This echoes 'The Ring and the Book'
"Do you see this square yellow Book, I toss
I'the air, and catch again, and twirl about
By the crumpled vellum cover, - pure crude fact
Secreted from man's life when hearts beat hard..."
Indeed, the romance between Christabel LaMotte and Randolph Henry Ash is similar to Robert Browning's affair with Julia Wedgewood which was revealed in the late 20th century. The general style of Browning's poetry is echoed by Ash especially Ash's extensive poem 'The Garden of Proserpina'.
However, it is important to remember that Byatt's characters are a construct and not any one figure.
If Ash is a construct of Browning, then Christabel LaMotte is an image of Christina Rossetti.
Rossetti's vivid imagery has been extended to the poems of LaMotte. And, her literary connections and famous family are echoes of Christina's involvement in the Pre-Raphaelite Brotherhood.
"I cannot tell you how it was;
But this I know: it came to pass
Upon a bright and breezy day
When may was young; ah, pleasant May!"
Rossetti's poem 'May' has many connotations within the novel as this was the name of Christabel's child and the premise of the Postscript.
"Two people met, on a hot May day, and never later mentioned their meeting. This is how it was."
Link to The Goblin Market with illustrations.