The Chiltern Class 172s were withdrawn in 2021 and were transferred to WMR. It is one of the few fleets I can think of that were fully introduced by a TOC and then fully withdrawn during the same franchise. I am not aware of all of these instances so it would be nice to see other fleets that had similar fates. The rules are that the entire fleet has to be introduced by the same TOC that withdraws it or transfers it to another operator, but if they come back to the same franchise it doesn't count, so the Class 180s and 458s don't count.