It would be good to get dates of -
When June bought the bike.
When Bamber found out Sheila & the twins were staying.
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Probably similar times.
The former it depends on which way you look at it.
The latter. It all depends. She was his sister. Whether from nevill, whether overhearing June speaking to nevill. Or Shelia herself. ( I look at it from your stance of June and Bamber mute with one another at all times )
Did Colin and Jeremy have a close relationship post Shelia and Colin's divorce, meet for a drink? Speak on the telephone? Any social activity of any kind?
Colin invited him to the party