As for price, I’ve heard £250k but have no idea if that is correct. But I notice that the description refers to the old tale about new 12” brake gear having to be developed for the J4 and to some extent this reflects John Thornley's remarks in Maintaining the Breed that the J4 had to await the 12” brakes of the L Type. Yet the F2, with 12” brakes, was introduced in August 1932 so it would seem that the story of the introduction of the J4 having to be delayed until bigger brakes were available is not quite right.