Theres no claim at all that these are based on his own drawings, or 'sketch books'.
the blurb says
"Working from photographic references, each image has been stripped back to a simpler and iconic portrayal of the subject,
which Johnny has then developed and energised with his characteristic freehand flourishes.' so no claim that he got involved at all until it was all printed out for him to colour in?
eg)
View attachment 335250
is from this old photo that is everywhere online
View attachment 335251
but with this written next to it by the gallery 'This portrait shows Dylan as handsome and heroic, at the height of his powers. But he also has his head bowed, with his eyes and ears open to the issues of humanity.'
Deep.