I wonder why Robert Boutflour said concerning the silencer, "The police had better have that"? Why would he think that they would be interested in the silencer? Was a plot simmering in his mind?
Also it is obvious that neither Basil Cock or Barbara Wilson were with them, because she said that she couldn't remember where they were. Also why did she mention the window? She said that the window was always left open for the cat. So why would Jeremy bother about shutting it? It was obvious if she thought about it the muddy marks were made by the cat.
Just one other observation. She said that Jeremy told them that they would get a surprise when they opened the safe. She said that they weren't surprised, they found some cannabis resin. DAH! Why were they not surprised at that I wonder?