That was the reason given for the kitchen window being opened. You haven't given a reason for missing off the end of the sentence in your previous post? The part where Ainsely states "There is no reason to believe that the bathroom window was opened" so HOW can he have been referring to the bathroom window when he mentioned the smell given the above comment?
Turing your own sentence on it's head and bringing it in line with Ainsley's comment above (the one you keep ignoring);
Yes, it does seem unlikely to unlock it without opening it, so likely that Jones didn't check it properly and it was unlocked all along.
There is no evidence that DCI Jones did not check the windows properly. Ainsley's comment that there was no reason to believe that the bathroom window had been opened does not conflict with Jones's evidence. He did not mean to say that it
couldn't have been opened, but only that there was no definite indication that it had been. He certainly didn't mean to imply that Jones made an error.
It's easy to see the purpose behind questioning Jones's evidence. The prosecution recognised that Taff Jones's evidence gives Bamber an alibi. It is a classic locked room alibi, so the prosecution needed a theory which gets around the problem.
The received view that Bamber exited via the kitchen window and closed it by banging it has recently been discredited. Photographs obtained by the defence show that the catch on the kitchen window has been pushed down to the Six O' Clock position, which could only be achieved by someone on the inside. A proposed alternative is that he got out through the bathroom window. But Taff Jones's evidence stands in the way. So the claim is made that Taff didn't check properly. But there is no evidence of that.
From the standpoint of probability it's far more likely that somebody opened the window after Jones made his examination and closed it again afterwards, a very ordinary thing to happen. On the other hand, DCI Jones would have had a lot of experience when it comes to making checks at the scene of a crime and is not likely to have made such a silly mistake.