What do I mean, when I say they were 'two clever, for their own good'?
They botched the attempt to merge the different silencers into the same one. In particular, they attributed the blood group evidence to the 'wrong' silencer ('DRB/1') which was not sent to the lab' to be checked for blood for the first time until the 20th September, 1985. 'DRB/1', was not the same silencer removed from the scene by 'Stan' Jones, on the 7th August, 1985 ('SBJ/1), nor was it the same silencer 'SJ/1' which 'Glynis' Howard examined on the 13th August, 1985. Neither was it the same silencer ('DB/1') sent back to the lab' on the 30th August, 1985, inside which was eventually found the crucial small flake of dried blood, from which subsequently produced blood group evidence was obtained between the 12th to 19th September, 1985...
'DRB/1', was not sent to the lab' until 'after' the blood group evidence had already been obtained from examination of the flake taken from the other ('DB/1') silencer, some eight days or so, 'before' silencer 'DRB/1' arrived at the lab'...