A signalling problem between Clapham Junction and London Waterloo is causing disruption to services between these stations.
National Rail said services may be cancelled, delayed by up to 40 minutes or amended to not call at all stations. This is now expected to continue until 2:30pm, having originally been expected to end by 12.30pm.
The rail operator said the routes affected are between Basingstoke/Guildford/Staines/Portsmouth Harbour Windsor & Eton Riverside and London Waterloo.
South West Trains said there would be reduced capacity on services into London due to the disruption.
Commuters took to Twitter to air their grievances about the disrupted service:
@SW_Trains @AnneMiltonMP Guildford to Waterloo. People standing! 10.17. Declassify first class please. Not acceptable. 5 coaches!!— Tadhg Bowe (@TadhgBowe) November 15, 2016
One tweeter even took inspiration from the delays and composed a short song: