(09 Oct 2023, 8:08 am)ifm001 wrote 722/723 were jointly operated until  mid to late 90s, (possibly even early 00s).

Think it was some time between 2003 & 2005 when the 723 was split in two at Durham / Framwellgate Moor, GNE continued running the 723 between Durham and Newcastle after the split for a little while before just being consolidated into the 21 whilst the Arriva 723 Darlo - Durham portion would become the 7 in 2008 (with some changes to the terminus in Durham over the years since, but the Arnison Centre was a regular fixture from 2006 to 2012).