It was brought up at the trial - where do you think the 'trick of light' came from? Bews was questioned about it!!
- Note also that Jeremy said nothing about seeing a figure nor did he mention anyone else seeing 'a figure'. The whole this was based on 'someone' suggesting there might have been 'movement'.
It wasn't based on 'someone' suggesting there might have been movement. Bews said Myalls said he saw someone.

Why would Jeremy have to see what Myalls saw? Did Bews see it? No. Myalls happened to look up at the window and thought he saw "someone". He then alerted Bews and Jeremy to the sighting.