At least two of the former members of the Conservative party (Ken Clarke and Dominic Grieve), who had the whip withdrawn following votes against the Government in early September 2019 and who are now sitting as independents, are (as of 25th September 2019) apparently still sitting on the Government benches, and still being referred to by members of the Government (specifically, the Attorney General) as "my Right Honourable and learned friend".
What are the conventions around who sits on the Government benches? As far as I know, it is surely not simply a matter of pledging to support the Government in votes of confidence and supply, as the DUP sit on the Opposition benches despite being in a confidence and supply agreement with the Government. Meanwhile, during the Conservative–Liberal Democrat coalition the Lib Dems sat on the Government benches.