(1) The hearsay rule and the tendency rule do not apply to evidence of a defendant's character if--(a) the evidence is evidence of an opinion about the defendant adduced by another defendant, and(b) the person whose opinion it is has specialised knowledge based on the person's training, study or experience, and(c) the opinion is wholly or substantially based on that knowledge.
(2) If such evidence has been admitted, the hearsay rule, the opinion rule and the tendency rule do not apply to evidence adduced to prove that that evidence should not be accepted.