I think the SWR suburban network is the only one in London now to have Guards
West mids on London Northwestern Railway have them but worth noting immediate inners are Overground which used to be Silverlink metro
Southern has no requirement for OBS staff into Victoria as the Brighton Mainline was excluded from the OBS agreement. GWR is DOO in the Thames Valley, C2C is all DOO, Greater Anglia only has Guards to Norwich, Chiltern only on loco hauled stuff, Southeastern metro is all DOO with long distance trains working DOO in the metro area, Overground and TFL, Thameslink Great Northern Gatwick Heathrow Express all DOO think that's it
coastal depots tend to be more militant it was the same with Barnham/Eastbourne presumably due to the lower cost of living and the more senior workforce